A disk device 1 comprising a disk cartridge 3 and a disk 2 accommodated
therein. The disk cartridge 3 includes a body case 1 with a window
for exposing a recording surface 5 of the disk 2; and provided with
a shutter body 25 to be moved in a manner capable of opening/closing the
window. The body case 11 is provided with a rotating body 30 in a
gear shape. Provided in a disk driving apparatus for recording a piece of information
into or reproducing the information from the disk 2 are: a guiding rib;
and an operation rack along the disk inserting direction. Upon insertion of the
disk device 1 into the disk driving apparatus, the guiding rib causes rotation
regulator 40 to rotate so that the rotation regulator 40 is disengaged
from the rotating body 30 and the operation rack engages with the rotating
body 30 to thereby rotate the rotating body 30, thereby opening/closing
the shutter body 25 via shutter opening/closing mechanism 35.
