Patent ID: 6948180

Claim:
A disk cartridge which accommodates an information-recording disk, the disk cartridge comprising: an upper case which has a first engaging section; a lower case which has a second engaging section engageable with the first engaging section and which defines a disk-accommodating section when the lower case overlaps with the upper case; and a movable section which is provided for at least one of the upper case and the lower case and which rotates the upper case relative to the lower case, wherein each of the upper case and the lower case is formed to be substantially circular while having at least a pair of parallel flat sections disposed at opposing positions on an outer circumference, an opening is provided on at least one of surfaces of the upper case and the lower case, and at least one of the upper case and the lower case has a plurality of ribs which surround the disk and which are formed by substantially concentric cylindrical surfaces, and the first engaging section and the second engaging section formed outside the ribs.