A disk cartridge includes a case which receives a disk thereon, a cover which is installed on the case and includes an opening, and a shutter which is movably installed in the case, in a lower direction of the disk, to open and close an aperture formed on the case. The disk cartridge has guide holes formed on the case along a trace of the shutter, and support members formed on the shutter. The support members are guided along the guide holes while having ends thereof interfering with peripherals of the guide holes. Therefore, since the peripherals of the guide holes interfere with the ends of the support members, the shutter is prevented from being deformed even where an external force is applied to the shutter through the aperture, in a closed state of the shutter.