PURPOSE: To use only one power source by detecting the insertion of a magnetic disc, switching the power transmission of the rotating power source by using a means interlocking with the operation of a switching lever interlocking with the transfer of the magnetic disc to clamp the disc and also switching the power transmission in the direction of clamp discharging by a disc discharging switch.

CONSTITUTION: A photoswitch 62 detects the insertion of the magnetic disc and generates an insertion signal and a motor 34 starts to rotate simultaneously. The rotation is transmitted to a worm gear 36 through an output shaft 35, starts the rotation of a roller 40 through bevel gears 38, 39, a gear 43, a coupling gear 45, and a gear 44 and transfers the disc 23 in the direction of an arrow (a). When the leading end of the disc 23 is contacted with a bending part 52c of a switching lever 52, a worm wheel 49 engaged with a lack gear 57 of the switching lever 52 starts to rotate in the direction of (b). Rotation of a cam 51 rotates a lever 58, a supporting arm 28 is pushed down by the lever 58 and the disc 23 is clamped by a center cone 30.