a calibration procedure in a calibration apparatus of the present invention will be described with reference to fig7 , 8 , and 9 . fig7 illustrates a time change in a pressure received by a pressure gauge serving as a standard device and a calibrated device when the calibrated device is calibrated in a step - wise calibration procedure . the pressure received by the calibrated device is illustrated by a solid line and the pressure received by the pressure gauge serving as the standard device is illustrated by a dotted line . time for acquiring measurement data and the pressure in a case of the calibrated device are illustrated by a black circle , and those in a case of the pressure gauge serving as the standard device are illustrated by a white circle . fig7 illustrates a procedure when step - wise calibration is performed on the calibrated device by using the present invention . fig7 ( a ) illustrates a case of using the present invention . whereas the calibrated device is subjected to pressure adjustment by using the step - wise calibration , the pressure gauge serving as the standard device is subjected to the pressure adjustment by using the 0 - a - 0 type procedure . when data is acquired at each calibration pressure point , the same pressure is applied to the pressure gauge serving as the standard device and the calibrated device . fig7 ( b ) illustrates a case of using the related art ( see fig2 ) . during the calibration , the same pressure is constantly applied to the pressure gauge serving as the standard device and the calibrated device . when performing the calibration by using the present invention , the pressure gauge serving as the standard device is calibrated in advance with the 0 - a - 0 type procedure . fig8 illustrates an example of the procedure when calibrating the pressure gauge serving as the standard device in advance . outputs at each calibration pressure point and a pressure zero state ( for example , in a case of a gauge pressure , an atmospheric pressure release state or a standard atmospheric pressure state may be acceptable ) are measured , and calibration values are calculated . fig8 illustrates a case where the calibration pressure points are increased in order . if the measurement in the pressure zero state is necessarily performed between the measurements at the calibration pressure points , the order of the calibration pressure points can be changed . as illustrated in fig5 and 6 , in the 0 - a - 0 type calibration procedure , influence of a pressure history is suppressed to be smaller . as a result , a hysteresis difference of the output is decreased and calibration conditions such as the maximum pressure are hardly affected . for this reason , in the present invention , even when the order of the calibration pressure points is changed , the output from the pressure gauge serving as the standard device is stable , thereby enabling a very accurate calibration . if the calibration apparatus is used , it is possible to set the order of the calibration pressure points not only step - wise but also arbitrarily . in addition , it is also possible to change pressure holding time at each calibration pressure point and in the pressure zero state . fig9 illustrates an application example of the calibration procedure of the present invention . fig9 ( a ) illustrates a case of changing the calibration pressure points of the calibrated device in random order . fig9 ( b ) illustrates a case where a time - dependent change in the calibrated device is measured while continuously applying a constant pressure to the calibrated device . at each calibration pressure point , outputs from the pressure gauge serving as the standard device and the calibrated device , to both of which the same pressure is applied , are compared with each other . the pressure gauge serving as the standard device is subjected to the pressure adjustment in the 0 - a - 0 type procedure . accordingly , the outputs are hardly affected by the order of the calibration pressure points , and it is possible to accurately perform the calibration as in a case of step - wise procedure illustrated in fig7 ( a ). in the above description , the pressure gauge serving as the standard device is restored to the pressure zero state ( for example , in a case of a gauge pressure , the atmospheric pressure release state or the standard atmospheric pressure state may be acceptable ). however , a state other than the pressure zero state , for example , a predetermined pressure state such as a pressure state close to pressure zero or a pressure state close to the maximum applied pressure , may be adopted . fig1 illustrates a first example of a calibration apparatus of the present invention . fig1 illustrates a calibration procedure and an operation of a shut - off valve in the calibration apparatus in fig1 . in the first example , the shut - off valve is arranged along a pressure pipe that connects the pressure gauge serving as the standard device and the calibrated device . a pressure generation control device is connected to each of the pressure gauge side serving as the standard device and the calibrated device side , across the shut - off valve . a release valve is connected to the pressure gauge side serving as the standard device , and is extended to a pressure release port for allowing the pressure zero state . the pressure gauge serving as the standard device , the shut - off valve , the release valve and the pressure generation control device , which are illustrated in fig1 , can be controlled by a measurement control unit . all operations can be automatically performed by inputting required parameters . the pressure gauge serving as the standard device may be internally installed in the calibration apparatus , or may be externally connected to the calibration apparatus by using a pipe . fig1 illustrates the calibration procedure of the pressure gauge serving as the standard device and the calibrated device , and operations of the shut - off valve and the release valve in order to realize the calibration procedure illustrated in fig7 ( a ) by using the apparatus of example 1 . pressure transmission is shut off between the pressure gauge serving as the standard device and the calibrated device by closing the shut - off valve at a calibration pressure point p i - 1 at time t 1 when data acquisition is completed . a pressure generation control device 1 is used to lower the pressure of the pressure gauge serving as the standard device to be zero . a pressure generation control device 2 is used to adjust the pressure of the calibrated device to the subsequent calibration pressure point p i . after the calibrated device reaches the pressure p i , the pressure is held to be constant until the data is acquired . the pressure gauge serving as the standard device is caused to be in the pressure zero state by opening the release valve ( time t 2 ), and after the waiting time , the output in the pressure zero state is measured ( time t 3 ). after the measurement , the release valve is closed and the pressure gauge serving as the standard device is subjected to the pressure adjustment to reach the subsequent calibration pressure point p i by using the pressure generation control device 1 . when reaching p i , the shut - off valve is opened , and the pressure transmission between the pressure gauge serving as the standard device and the calibrated device is allowed ( time t 4 ). after the waiting time , the output of the pressure gauge serving as the standard device and the calibrated device is measured at p i . also when the pressure is adjusted to the subsequent calibration pressure point , the same procedure is repeated ( a state of time t 5 in fig1 corresponds to a state of time t 1 in a case where the pressure is adjusted to the subsequent calibration pressure point ). fig1 illustrates comparison between the calibration result using the calibration apparatus illustrated in fig1 and the operation procedure illustrated in fig1 and the calibration result using the dead weight pressure balance . the calibration results by using the calibration apparatus in which the dead weight pressure balance illustrated in fig1 serves as the standard device in the step - wise calibration procedure are illustrated by the black circle and the solid line . the calibration results performed by using an invented product are illustrated by the white circle and the dotted line . the calibration results in a case where the maximum pressure is changed into three types are illustrated in fig1 ( a ), 12 ( b ), and 12 ( c ). the pressure gauge serving as the standard device is calibrated with the 0 - a - 0 type calibration procedure of 100 mpa in maximum pressure , and the same calibration value is used in all of three cases . in every case , the calibration results using the invented product excellently coincide with the calibration results using the deadweight pressure balance as the standard device . in this manner , it is found out that the invented product can be used to evaluate the influence affected by the maximum pressure of the calibration when the calibrated device is calibrated with the step - wise procedure , in the same way that the dead weight pressure balance is used . a pressure gauge serving as a standard device , the pressure gauge being calibrated in advance by a calibration procedure to repeat necessarily restoring a pressure zero state after data acquisition at each calibration pressure point , and adjusting pressure to a subsequent calibration pressure point ; wherein one end of the pressure pipe is connected to a pressure gauge that is a calibrated device , and the other end thereof is extended to a pressure release port through a release valve , wherein the pressure gauge serving as the standard device and a pressure generation control device 1 are connected between , in the pressure pipe , the shut - off valve and the release valve , wherein a pressure generation control device 2 is connected between , in the pressure pipe , the shut - off valve and the calibrated device , acquiring data at a calibration pressure point when the shut - off valve is opened , the release valve is closed , and the pressure gauge serving as the standard device and the calibrated device are in the pressure transmission state therebetween ; after the data is acquired , closing the shut - off valve , lowering by the pressure generation control device 1 the pressure of the pressure gauge serving as the standard device to zero , opening the release valve , and adjusting by the pressure generation control device 2 the pressure of the calibrated device nearly to a subsequent calibration pressure point ; next , closing the release valve , and adjusting by the pressure generation control device 1 the pressure of the pressure gauge serving as the standard device to the subsequent calibration pressure point ; and if the subsequent calibration pressure point is reached , opening the shut - off valve , making the pressure gauge serving as the standard device and the calibrated device in the pressure transmission state , and acquiring the data at the subsequent calibration pressure point . fig1 illustrates a second example of a calibration apparatus of the present invention . fig1 illustrates a calibration procedure and an operation of shut - off valves in the calibration apparatus in fig1 . in the second example , two shut - off valves are connected along the pressure pipe that connects the pressure gauge serving as the standard device and the calibrated device . one pressure generation control device is connected to a pipe between the two shut - off valves . a release valve is connected to the pressure gauge side serving as the standard device , and is extended to a pressure release port for allowing the pressure zero state . the pressure gauge serving as the standard device may be internally installed in the calibration apparatus , or may be externally connected to the calibration apparatus by using a pipe . the pressure gauge serving as the standard device , the shut - off valves and the pressure generation control device , which are illustrated in fig1 , are controlled and enabled to acquire the data by the measurement control unit . thus , it is possible to automatically perform all the operations by inputting required parameters . fig1 illustrates a calibration procedure of the pressure gauge serving as the standard device and the calibrated device , and operations of the shut - off valves 1 and 2 and the release valve in order to realize the calibration procedure illustrated in fig7 ( a ) by using the apparatus of example 2 . let t 1 be the time when data measurement is completed at the calibration pressure point p i - 1 . when the data is acquired , the shut - off valves 1 and 2 are in the opened state . however , at time t 1 , the shut - off valve 2 is closed , and the pressure of the pressure gauge serving as the standard device is lowered to be zero by using the pressure generation control device . the release valve is opened , the pressure gauge serving as the standard device is caused to be in the pressure zero state , and then the shut - off valve 1 is closed . the pressure transmission between the pressure gauge serving as the standard device and the pressure generation control device is shut off ( time t 2 ). after the waiting time , the output from the pressure gauge serving as the standard device in the pressure zero state is measured . in the meanwhile , the pressure is adjusted to the pressure p i - 1 by the pressure generation control device . when the pressure is equal to the pressure p i - 1 of the calibrated device , the shut - off valve 2 is opened ( time t 3 ). thereafter , the pressure of the calibrated device is adjusted to the subsequent calibration pressure point p i , and the pressure is maintained to be constant . punctually to the time when the measurement of the pressure gauge serving as the standard device is completed in the pressure zero state , the shut - off valve 2 is re - closed at time t 4 , and the pressure of the pressure generation control device is lowered to be zero while maintaining the pressure of the calibrated device to be p i . after the measurement of the pressure gauge serving as the standard device is completed in the pressure zero state , the release valve is closed ( time t 5 ). the shut - off valve 1 is opened , the pressure transmission is allowed between the pressure generation control device and the pressure gauge serving as the standard device , and the pressure is adjusted to the subsequent measurement pressure p i . when the pressure p i is reached , the shut - off valve 2 is opened and the pressure transmission is allowed among the pressure gauge serving as the standard device , the pressure generation control device and the calibration device ( time t 6 ). after the waiting time , outputs from the pressure gauge serving as the standard device and the calibrated device are measured at the pressure p i . also when the pressure is adjusted to the subsequent calibration pressure point , the same procedure is repeated ( the state of time t 7 in fig1 corresponds to the state of time t 1 in a case where the pressure is adjusted to the subsequent calibration pressure point ). a pressure gauge serving as a standard device , the pressure gauge being calibrated in advance by a calibration procedure to repeat necessarily restoring a pressure zero state after data acquisition at each calibration pressure point , and adjusting pressure to a subsequent calibration pressure point ; a pressure pipe along which a shut - off valve 1 and a shut - off valve 2 are arranged ; and wherein one end of the pressure pipe is connected to a pressure gauge that is a calibrated device , and the other end thereof is extended to a pressure release port through a release valve , wherein the shut - off valve 1 is arranged nearer the release valve relative to the shut - off valve 2 , wherein the pressure gauge serving as the standard device is connected between , in the pressure pipe , the shut - off valve 1 and the release valve , wherein a pressure generation control device is connected between , in the pressure pipe , the shut - off valve 1 and the shut - off valve 2 , acquiring data at a calibration pressure point when the shut - off valve 1 and the shut - off valve 2 are opened , the release valve is closed , and the pressure gauge serving as the standard device and the calibrated device are in the pressure transmission state therebetween ; after the data is acquired , closing the shut - off valve 2 , lowering by the pressure generation control device the pressure of the pressure gauge serving as the standard device to zero , opening the release valve , then closing the shut - off valve 1 , and shutting off the pressure transmission between the pressure gauge serving as the standard device and the pressure generation control device ; next , adjusting the pressure by the pressure generation control device , and when the immediately preceding calibration pressure point is reached , opening the shut - off valve 2 , and adjusting the pressure nearly to a subsequent calibration pressure point ; next , after the shut - off valve 2 is closed , lowering the pressure of the pressure generation control device to zero ; next , closing the release valve , opening the shut - off valve 1 , making the pressure generation control device and the pressure gauge serving as the standard device in the pressure transmission state , and adjusting the pressure to the subsequent calibration pressure point ; if the subsequent calibration pressure point is reached , opening the shut - off valve 2 , making the pressure gauge serving as the standard device and the calibrated device in the pressure transmission state , and acquiring a data at the subsequent calibration pressure point . in the above - described examples , as a predetermined pressure state , the description has been made such that the pressure gauge serving as the standard device is restored to the pressure zero state ( for example , in a case of a gauge pressure , the atmospheric pressure release state or the standard atmospheric pressure state may be acceptable ). however , a state other than the pressure zero state , for example , such as a pressure state close to pressure zero or a pressure state close to the maximum applied pressure may be adopted .