embodiments of the present invention will be described below with reference to the attached drawings . with reference to fig1 to 3 , a care support apparatus in a first embodiment of the present invention will be described . as depicted in fig1 , a care support apparatus 1 includes , on a right side surface of a main body 2 , a first link 3 r provided with a first wheel 5 r at a lower end of the first link 3 r and a second link 4 r engaged with an intermediate portion of the first link 3 r and provided with a second wheel 6 r at a lower end of the second link 4 r ; the first link 3 r and the second link 4 r serve as right leg links . the care support apparatus 1 includes , on a left side surface of the main body 2 , a first link 3 l provided with a first wheel 51 at a lower end of the first link 3 l and a second link 4 l engaged with an intermediate portion of the first link 3 l and provided with a second wheel 6 l at a lower end of the second link 4 l ; the first link 3 l and the second link 4 l serve as left leg links . the second wheels 6 r and 6 l may be configured to function as casters or turning wheels . at the front of the care support apparatus 1 , seat members 70 r and 70 l rotatably held by the main body 2 are arranged . the seat members 70 r and 70 l each rotate about a rotation axis so as to reduce the distance between the seat members 70 r and 70 l to approach each other , thus providing a seat surface 7 on which the care receiver can sit . a handle 8 is provided at an upper portion of the main body 2 . as seen in a sectional view of the right leg link depicted in fig3 , the first link 3 r and the main body 2 are rotatably engaged with each other via a second axis p defined by two bearings 9 r . the first link 3 r is driven by a motor 10 r to rotate around the second axis p with respect to the main body 2 . the second link 4 r and the first link 3 r are rotatably engaged with each other via a first axis q defined by two bearings 11 r . the second link 4 r is driven by a motor 7 r to rotate around the first axis q with respect to the main body 2 . in the left leg link , each of the first and second links 3 l and 4 l is similarly rotated by a motor . in a side view of the right leg link depicted in fig2 , an angle α 1 is subtended between a line m perpendicular to a ground surface f of the care support apparatus 1 in a low form depicted by a solid line and a straight line connecting the second axis p with the center of rotation of the first wheel 5 r . an angle β 1 is subtended between a straight line connecting the first axis q with the center of rotation of the first wheel 5 r and a straight line joining the first axis q with the center of rotation of the second wheel 6 r . in this case , the distance between the center of rotation of the first wheel 5 r and the center of rotation of the second wheel 6 r is denoted by l 1 . in this state , the second link 4 r is rotated clockwise by the motor 7 r so as to set an angle β 2 between the straight line joining the first axis q with the center of rotation of the first wheel 5 r and the straight line joining the first axis q with the center of rotation of the second wheel 6 r . at the same time , the first link 3 r is rotated counterclockwise by the motor 10 r so as to set an angle α 2 between the line m and the straight line joining the second axis p with the center of rotation of the first wheel 5 r . then , the form is changed as depicted by a dashed line to change the distance between the center of rotation of the first wheel 5 r and the center of rotation of the second wheel 6 r to l 2 , increasing the distance of the second axis p from the ground surface f . in this case , when the relationship between the rotation angles of the links is expressed by β 1 − β 2 = 2 ×( α 1 − α 2 ), the angle of the main body 2 with respect to the ground surface f is maintained constant . when used to support the care receiver &# 39 ; s transfer or stand - up , the care support apparatus 1 is operated as follows . when the main body 2 is low and the seat member 70 r and the seat member 70 l are not close to each other and open in a lateral direction and do not form the seat surface 7 , the care receiver in a sitting position who is sitting in a chair or the like grips the handle 8 , and assumes a position in which the care receiver &# 39 ; s upper body lies over the main body 2 , as needed . a care receiver operates an operating member not depicted in the drawings to rotate the first link 3 r and the second link 4 r to raise the main body 2 to a desired height as depicted in fig5 . when the care receiver assumes a half - crouching or standing position , the care receiver stops the rotation . in an initial stage of this operation , a strong forward pulling force acts on the care support apparatus 1 in order to pull up the care receiver . however , the distance between the first wheel 5 r and the second wheel 6 r is long , and the care support apparatus 1 is thus stable . the care receiver moves and turns the care support apparatus 1 to move to a desired position . at this time , the distance between the first wheel 5 r and the second wheel 6 r is shortened to reduce a moment of force acting as resistance at the time of the turning , thus facilitating the turning . furthermore , when the second wheel 6 r is a turning wheel , the turning radius of the care support apparatus 1 can be reduced . the care receiver operates the operating member to rotate the first link 3 r and the second link 4 r to lower the main body 2 to a desired height . when the care receiver assumes the sitting position at a desired position of the apparatus , the care receiver stops the rotation . when the care support apparatus 1 is used for gait training for the care receiver , the care receiver in the standing position grips the handle 8 to support the upper body , while pushing the care support apparatus 1 to move in a desired direction as depicted in fig5 . at this time , the main body 2 is at a high position , and the distance between the first wheel 5 r and the second wheel 6 r is short . this reduces a moment of force acting as resistance when the care support apparatus 1 changes its direction , which allows the care receiver to more easily operate the care support apparatus 1 . when the care receiver is tired from the gait training , the seat members 70 r and 70 l are rotated around attachment shafts thereof to reduce the gap between the seat members 70 r and 70 l to move the seat members 70 r and 70 l closer to each other , thus forming the seat surface 7 as depicted in fig6 . subsequently , the position of the main body 2 is lowered to allow the care receiver to sit on the seat surface 7 to take a rest . moreover , in the form depicted in fig6 , the care support apparatus 1 can be used as a self - propelled wheelchair by adding driving means to the first wheels 5 r and 5 l to control the rotation of the first wheels 5 r and 5 l . as depicted in fig7 and fig8 , a care support apparatus 100 in the second embodiment corresponds to the care support apparatus 1 of the first embodiment in which a third link is added to one end of the first link 3 r . the form of the care support apparatus 100 thus has an increased degree of freedom . in a sectional view of a right leg link depicted in fig8 , a third link 106 r and the main body 2 are rotatably engaged with each other via a fourth axis o defined by the two bearings 9 r . the third link 106 r is rotationally driven by the motor 10 r with respect to the main body 2 . a first link 103 r and the third link 106 r are rotatably engaged with each other via a third axis r defined by two bearings 112 r . the first link 103 r is rotationally driven by a motor 105 r with respect to the third link 106 r . the first link 103 r and a second link 104 r are rotatably engaged with each other via a first axis q defined by two bearings 113 r . the second link 104 r is rotationally driven by a motor 107 r with respect to the first link 103 r . in a left leg link , a first link , a second link , and a third link are similarly rotationally driven by motors . in a side view of the right leg link depicted in fig7 , an angle α is subtended between the line m perpendicular to the ground surface f of the care support apparatus 100 and a straight line joining the fourth axis o with the third axis r . an angle β is subtended between a straight line connecting the third axis r with the center of rotation of the first wheel 5 r and a straight line joining the first axis q with the center of rotation of the second wheel 6 r . an angle γ is subtended between the first link 103 r and the third link 106 r . the angle α is controlled by the motor 10 r , the angle β is controlled by the motor 107 r , and the angle γ is controlled by the motor 105 r . an appropriate combination of the three angles allows the care support apparatus 100 to assume a form that matches the care receiver &# 39 ; s positions ranging from the sitting position to the standing position . in the description of the embodiments , the main body 2 is at the constant angle with respect to the ground surface f . however , the angle may be changed when the form of the care support apparatus is changed . when the care support apparatus 1 is not used as a wheelchair , the seat surface 7 may be removed from the structure .