The present invention relates to a disk cartridge in which a disk-like recording medium such as an optical disk, a magneto-optical disk and a magnetic disk is accommodated within a disk compartment of a cartridge housing, a disk recording medium device in which the disk-like recording medium is accommodated in advance within the disk compartment so as to become freely rotatable and a disk recording and/or reproducing apparatus for recording and/or reproducing information by using this disk recording medium device. According to a disk cartridge of the present invention, there is provided a disk cartridge composed of a cartridge housing including an upper shell, a rotary member and a lower shell, a shutter member movable between the opening position and the closing position to open and close an opening portion of the cartridge housing and a shutter fixing means for holding the shutter member in the closed state at the closing position and in which the shutter member is held in the opened state at the opening position by the shutter fixing means. According to the present invention, there is no risk that vibrations generated from an external apparatus will be transmitted to the disk cartridge and the like through an open and hold mechanism. Thus, malfunctions caused by vibrations can be prevented or suppressed when information is written in and read out from the disk-like recording medium.