To ensure centering of a different-size discoid recording medium by providing at least two centering members different in position in accordance with the size of a discoid recording medium to be centered, and a detection member for detecting the size of the disk shaped recording medium and controlling the positions of the centering members in accordance with the detected size of the disk shaped recording medium.

When an 8cm-CD 102 is pulled into a reproducing part, the CD 102 is passed through the space between detecting pins 282 since the space between the detecting pins 282 is set larger than the outer diameter of the CD 102. When the CD 102 is pulled inside leaning largely to either left or right, its outer circumferential periphery is brought into contact with either of the detecting pins 282 and is pressed outwardly. The outer circumferential periphery of the CD 102 is brought into contact with centering pins 294, so that the CD 102 is centered, and in this state, a pin 312 to be pressed is pressed backward, and a trigger lever 310 is slightly turned to make a pressing periphery 316 press a piece 321 to be pressed of a relay lever 320.