embodiments of the present invention will be described below with reference to the accompanying drawings . fig1 illustrates , in schematic terms , the loading mechanism of an optical disk reproducing apparatus according to the embodiment of the present invention . fig1 shows that a disk 3 has been inserted from above the reproducing apparatus by an optical disk insertion means that includes a disk insertion port and then transferred to the reproduction position . the optical disk reproducing apparatus is comprised of a main body 1 , a disk holder 6 and a disk holder driving means 4 . the disk holder 6 , which is an optical disk transfer means in the present invention , transfers the disk 3 from its disk insertion port to a reproduction means 5 . the reproduction means 5 includes , among other elements , an optical pick - up , a turntable and a spindle motor and reproduces the disk 3 . the disk holder driving means 4 drives this disk holder 6 . in other words , the disk holder 6 is caused by the driving force of the disk holder driving means 4 to move in the vertical direction between a disk insertion position ( upper position in fig1 ) and a disk reproduction position ( lower position in fig1 ). fig2 shows the back of the main body 1 of the optical disk reproducing apparatus , illustrating schematically the arrangement of the driving system of the optical disk insertion means and the optical disk transfer means of the optical disk reproducing apparatus of one embodiment of the present invention . the driving system transmits the rotation of a motor 7 to a cam gear 11 via a belt 8 , a pulley gear 9 and a gear 10 . thus , the cam gear 11 is turned by the rotation of the motor 7 . a slide plate 12 is engaged with guide pins 15 and 16 that are fastened to a chassis 2 inside the main body 1 , and thus the slide plate 12 is provided so as to slide . a slide plate shaft 12 a which is fastened to the slide plate 12 is engaged with a cam groove 11 a of the cam gear 11 , so that the slide plate 12 is caused to slide in the vertical direction along the guide pins 15 and 16 when the cam gear 11 is rotated . to both side surfaces of the chassis 2 , slide cams 18 are attached so as to slide in the vertical direction . both end portions 12 b and 12 c of the slide plate 12 are respectively engaged with grooves 28 a and 28 b formed in the slide cams 18 . thus , when the slide plate 12 is moved in the vertical direction , the slide cams 18 are also moved in the vertical direction . in response to the vertical movement of the slide cams 18 , the disk holder 6 is moved in the vertical direction between position a ( the disk reproduction position ) and position b ( disk insertion position ) in fig1 . the disk holder 6 is moved upward and downward while maintaining a position that is parallel to the front surface of a door 19 ( described later ). fig3 ( a ), 3 ( b ) and 3 ( c ) illustrate the operation of an disk cover that is the door 19 equipped with the disk holder 6 . the disk cover or the door 19 of the optical disk reproducing apparatus of one embodiment of the present invention is caused to move forward and pivot toward the front ( which is on the left side of each of fig3 ( a ), 3 ( b ) and 3 ( c )) of the reproducing apparatus as a result of the vertical movement of the slide cams 18 . more specifically , in fig3 ( a ), the slide cams 18 ( only one slide cam 18 is shown ) are in the lowermost position of their vertical movement . in this lowermost position of the slide cams 18 , the disk holder 6 is in position a in fig1 , and the optical disk 3 is in the position where it is reproduced by the reproduction means 5 ( there is no rotation of the disk holder driving means 4 ). the door 19 is in the closed position in the apparatus main body 1 . in this state , the front surface of the door 19 and the front surface of the apparatus main body 1 coincide or flush with each other as shown in fig3 ( a ). next , as shown in fig3 ( b ), when the slide cams 18 are moved to roughly a central position in the vertical direction ( as a result of the rotation of the motor 7 shown in fig2 ), door shafts 19 a and 19 b that are fastened to the door 19 are pushed by the cam grooves 18 a and 18 b of the slide cams 18 ; and the shafts 19 a and 19 b are guided along grooves 2 a and 2 b formed in the chassis 2 . the cam groove 18 a is formed obliquely with its rear end being higher than the front end , and the cam groove 18 b is formed so as to have an oblique section in which the rear end is higher than the front end and a straight section that extends downward from the front end . as a result , the door 19 is slid or moved toward the front ( the left side in fig3 ( b )) of the reproducing apparatus and project out from the front surface of the reproducing apparatus . in this state as well , the disk holder 6 is in position a shown in fig1 ( there is no rotation of the disk holder driving means 4 ). in fig3 ( c ), the motor 7 shown in fig2 rotates . the slide cams 18 are thus moved further upward , the door shaft 19 a is pushed toward the front of the main body 1 by the oblique cam groove 18 a , and the door shaft 19 b enters the straight section ( which is in downward direction in fig3 ( c )) of the cam groove 18 b of the slide cam 18 . as a result , the movement of the door shaft 19 b ( and thus the door 19 ) toward the front stops . in the structure of the shown embodiment , the door 19 as a whole pivots about an imaginary axis of rotation ( as if there were a pivot point ). more specifically , when the optical disk insertion means ( 34 ) and the optical disk transfer means ( 6 ) are caused to pivot toward the front of the main body , these elements pivot about an imaginary axis of rotation p that is set further toward the front of the main body than the connection point of a connecting means installed between the lower portion of the optical disk transfer means ( 6 ) and the chassis 2 inside the main body . more specifically , the connecting means comprises the door shaft 19 b provided in the lower portion of the optical disk transfer means 6 ( or the door 19 ) and the grooves 2 b of the chassis 2 with which the door shaft 19 b is engaged and guided . during this operation ( during the operation of fig3 ( b )→ 3 ( c )), the motor 7 shown in fig1 rotates , and the disk holder 6 which is disposed in a position parallel to the front surface of the door 19 is moved from position a to position b in fig1 . as a result , the disk 3 held in the disk holder 6 is transferred in a state in which the disk 3 is inclined toward the front of the main body and is removed from the upper position of the main body 1 as shown in fig1 . when the disk 3 is inserted into the reproducing apparatus and reproduced , an operation that is the opposite from the operation described above is performed . in fig4 , the door 19 ( the optical disk insertion means 34 ) includes an optical disk transfer means 35 ( the disk holder 6 ) and a disk insertion port 30 . when an optical disk 3 is inserted into the optical disk insertion means 34 that is the door 19 from the disk insertion port 30 , or when an optical disk 3 is removed from the disk insertion port 30 , it is not necessary to put fingers 32 of hand 31 of the user gripping the optical disk 3 into the open space 33 ( unlike the case to put a cassette tape into a cassette tape recorder ). accordingly , the opening angle θ of the door 19 for the open space can be set at a small angle . the opening angle θ is the angle formed by the front surface of the main body 1 and the optical disk recorded surface 36 of the optical disk 3 . since the opening angle θ of the door 19 is small , dust can be avoided from entering into the reproducing apparatus , lowering the causes of troubles . furthermore , the hand 31 of the user does not contact the optical disk recorded surface 36 of the optical disk 3 ; instead , as seen from fig4 , the optical disk 3 can be gripped from the printed label surface side and put in the disk insertion port 30 from above . accordingly , no inadvertent contact of the fingers 32 with the optical disk recorded surface 36 of the optical disk 3 will occur , and fingerprints and scratches on the optical disk recorded surface 36 can be avoided . furthermore , since the angle θ is small , the reproducing apparatus can be made thinner and more compact . moreover , the disk insertion port 30 can be visually checked when the optical disk 3 is inserted and removed , and the insertion and removal of the optical disk can be easily accomplished . as seen from the above , in the present invention , the optical disk insertion means ( the door 19 ) into which an optical disk is inserted tilts toward the front with its lower portion acting as an axis of rotation , and then , the optical disk transfer means ( the disk holder 6 ) is moved up and down in an inclined state as indicated by arrow in fig4 . accordingly , when an optical disk is inserted or removed , the recorded surface of the optical disk tends not to contact the disk insertion port , and scratching of the recorded surface can be avoided . furthermore , as seen from fig4 , the user can insert and remove an optical disk by gripping the optical disk from the printed label surface side of the optical disk . accordingly , inadvertent fingerprints or scratches on the recorded surface of the optical disk can be avoided . in addition , since optical disks are inserted and removed with the optical disk insertion means tilted toward the front , the disk insertion port can be visually checked even when the reproducing apparatus is located in a high position on a wall . the insertion and removal of the optical disk can be easily accomplished . furthermore , the optical disk insertion means into which an optical disk is inserted is moved forward from the main body , and then the optical disk insertion means pivots about an imaginary axis of rotation located in a position on the front surface of the main body . accordingly , even if the optical disk playback apparatus has a greatly reduced thickness , the position of the front surface of the main body and the position of the front surface of the optical disk insertion means are flush with each other when the optical disk insertion means is closed . moreover , it is possible to take such a structure that the gap between the lower portion of the optical disk insertion means and the front surface of the main body is small or no such gap is formed . since the disk insertion port enters the interior of the main body of the reproducing apparatus when the optical disk insertion means is closed , the entry of dust through the disk insertion port is prevented , and it is not necessary to provide an opening - and - closing means for the disk insertion port . furthermore , since the operation that opens and closes the optical disk insertion means is unique , it increases the desire of the user to purchase the apparatus .