a disc;

a cartridge body having the disc rotatably housed therein and having formed therein a write and/or read aperture through which part of the disc is exposed to outside in a range between inner and outer radii thereof;

a shutter member including a shutter portion to open and close the write and/or read aperture and installed to the cartridge body to be movable between a position to close the write and/or read aperture and a position to open the write and/or read aperture;

a connecting arm extending from one lateral side of the shutter member;

an elastic moving piece installed to extend along the connecting arm with a base end thereof being fixed to a free end of the connecting arm, having a pressing piece provided at a base end of the shutter member to face a window formed in a movement guide piece opposite to a one lateral side of the cartridge body and forced for the pressing piece to project to outside the cartridge body through the window; and

a shutter movement limiting member provided pivotably on the shutter member to limit, when the shutter member is in the position to close the write and/or read aperture, the shutter member from moving in a direction to open the write and/or read aperture by engaging an engagement portion on a movement limiter provided on the cartridge body, and to pivot along with the elastic moving piece in a direction disengaging the engagement portion from the movement limiter when the elastic moving piece is pressed by means of the pressing piece against a force applied to the latter,

the engagement portion being formed circular at a side of the movement limiter.