PURPOSE: To provide a flexible disk drive device having an extremely excellent operability, which enables sufficiently to correspond to even various operation situations.

CONSTITUTION: A projection part 10-1 being engaged to a protective shutter 16-1 of a disk cartridge 16 is provided on a shutter opener 10. At an ejecting time of the disk cartridge 16 by a knob operation, even though an interlock between a frame engaged part and the disk cartridge 16 is released, the disk cartridge 16 is positioned by being engaged the projection part 10-1 of the shutter opener 10 to the protective shutter 16-1. If a shocked ejecting operation is carried out with the knob, the disk cartridge 16 is not ejected incorrectly. The disk cartridge is not ejected erroneously and also damage of the head, etc., can be reduced to the utmost.