PURPOSE: To perform the loading and unloading of a cartridge to and from the device and the movement of a magnetic field supplying means without interfering with each other by driving in turn a moving means or a releasing means with the rotation of a driving motor.

CONSTITUTION: The device has the releasing means 29 for driving a loading and unloading means in the direction of withdrawing a recording disk 2 from a motor 16 after engaging with the loading and unloading means, the magnetic field supplying means for supplying a magnetic field on the recording disk 2, the moving means for moving the magnetic field supplying means in the device, the driving motor 16 for driving the releasing means 29 or the moving means and a transmission means for transmitting the power of the driving motor 16 to the releasing means 29 or the moving means. In this case, either a 1st transmission state for transmitting the power only to the releasing means 29 or a 2nd transmission state for transmitting the power only to the moving means is effective for the transmission means. By this method, the movement of the magnetic field supplying means and the releasement of the cartridge can be carried out in turn only by a continuous rotation of the motor in combination of the single motor, the transmission means and the releasing means.