Disk cartridge

A disk cartridge to be inserted into a disk drive apparatus through an insertion opening of the disk drive apparatus upon use, the disk cartridge comprising:

• a shell with at least an opening portion through which a disk table provided in the disk drive apparatus is inserted;
• a disk-shaped recording medium rotatably housed in the shell;
• four positioning holes or four positioning grooves formed on the shell as positioning portions to the disk drive apparatus,
• wherein said four positioning holes or said four positioning grooves are designated as a first positioning portion, a second positioning portion, a third positioning portion and a fourth positioning portion, respectively, and
• wherein when defined that two directions which are perpendicular to a thickness direction of the disk-shaped recording medium are designated as an X direction and a Y direction, and further an inserting direction to the insertion opening and an opposite direction to the inserting direction are designated as the Y direction;
• said first positioning portion and said second positioning portion are formed at a same position in the X direction;
• said third positioning portion and said fourth positioning portion are formed at a same position in the X direction but different from the position of said first positioning portion and said second positioning portion;
• said first positioning portion and said third positioning portion are formed at a same position in the Y direction;
• said second positioning portion and said fourth positioning portion are formed at a same position in the Y direction but different from the position of said first positioning portion and said third positioning portion;
• and wherein
• at least two of said four positioning portions are used in positioning the disk cartridge to the disk drive apparatus at insertion of the disk cartridge into the disk drive apparatus through the insertion opening.