MAGNETIC DISK DEVICE

PURPOSE:To raise dust preventive performance by a simple structure by providing a double dust preventive door which is closed in a state that there is no gap, before a cassette is installed to a magnetic disk cassette inserting port of a device. CONSTITUTION:Before a magnetic disk cassette 1 is installed, upper and lower dust preventive doors 19, 20, and closed in a state that the lower end of the dust preventive door 19 of the upper side contacts with the outside of a bend part 20a of the upper end of the dust preventive door 20 of the lower side by force of a torsion coil spring 23, and there is no gap. In this state, when the magnetic disk cassette 1 is intalled, the dust preventive doors 19, 20 are opened up and down by being pushed. In this case, the upper and lower dust preventive doors 19, 20 are overlapped, width of the door is large by that portion, and a distance l3 between the door and the upper face of the magnetic disk cassette 1 positioned at the upper side of a cassette inserting port 18a of a shaft 21 can be made large. Accordingly, since an arm of moment is lengthened, the doors are opened in a state that a sense of incongruity is scarcely felt, and the magnetic disk cassette can be installed very easily.