Abstract: A cartridge includes a shutter movably mounted along and on outside surfaces of a cartridge box for opening or closing a central hole and a head slit together, a slider for driving the shutter, and guide grooves provided outside a receptacle for a disk and serving to guide the slider. The shutter normally closes the central hole and the head slit to permit the cartridge to completely surround the disk, thereby preventing entry of dust from the outside. Even when the slider is broken by accident, the disk is immune from scratches to be constantly held in a good state since the slider is moved on the outside of the receptacle. Moreover, a drive for the shutter is provided forwardly of the center of the receptacle to enable increasing the recording capacity of the disk and miniaturizing the cartridge.