Disc cartridge having a shutter that includes a convex portion protruding into a center hole of the disc

A disc cartridge includes a cartridge body having a disc storage portion, a chucking opening and a head opening. The disc storage portion has a disc window and a bottom and stores a disc, having first and second sides, therein so that the disc is rotatable in the disc storage portion and that the first side of the disc is exposed. The chucking opening is formed on the bottom of the disc storage portion so as to get the disc chucked externally. The head opening is also formed on the bottom of the disc storage portion so as to allow a head, which reads and/or writes a signal from/on the second side of the disc, to access the second side of the disc. A shutter is supported to, and movable with respect to, the cartridge body so as to expose or cover at least the head opening.