PURPOSE: To reduce the number of parts, to simplify assembly and to reduce the production cost by allowing the titled device to execute a locking function to a lock lever and a release preventing function to a cassette discharging lever only by one spring.

CONSTITUTION: Before charging a magnetic disc cassette 2, a cassete eject lever 3 is pulled left by the tensile force of a spring 10 and a lock lever 12 is pressed and contacted to/with the side edge 3d of the cassette eject lever 3 by the pressing force of a spring 17. If the cassette 2 is guided and inserted by a guide 1 under said status, the leading end of the cassette 2 is brought into contacted with stopper 11 of the eject lever 3 and the cassette 2 is pushed forward against the tensile force of the spring 10. Consequently, the eject lever 3 advances and a projection 12a of the lock lever 12 is engaged with a step part 3c to lock the lock lever 12. At that time, the release of the eject lever 3 is prevented by U-shaped bending parts 17a, 17b formed on both ends of the spring 17.