<p>A disk cartridge includes a cartridge body and a lid. The cartridge body includes: first and second principal surfaces opposed to each other; a storage space to store a disklike data storage medium; windows cut through the first and second principal surfaces to partially expose the data storage medium in the storage space; an opening for removing the data storage medium from the storage space; and write-protect indicator holes cut through the first and second principal surfaces to prohibit writing on the data storage medium stored. The lid is provided to cover and uncover the opening of the cartridge body. The cartridge body is shaped such that both of the first and second principal surfaces can be opposed to a pickup of an optical disk drive when the cartridge is loaded into the drive. Of the two write-protect indicator holes of the first and second principal surfaces, only the hole of the second principal surface is provided with a write enable/disable selecting mechanism that covers or uncovers the write-protect indicator hole.</p>
