Patent ID: 7342747

Claim:
A recording disk cartridge comprising: a plurality of flexible recording disk media integrally rotatably housed within a cartridge case, the case comprising: a lower plate for configuring a lower wall parallel to said plurality of the recording disk media; at least one inner plate that is stacked and fixed on said lower plate, and partitions said plurality of the recording disk media; and an upper plate that is stacked and fixed on said inner plate, and configures an upper wall of said cartridge case, wherein the cartridge further comprises a plurality of center cores each of which is provided for each recording disk medium and has a main body portion and a collar part widening in an outer diameter direction from the main body portion; each recording disk medium is affixed to the collar part of the respective center core; and each inner plate has a central opening configured to accommodate the main body portion of the center core and has a recess part along a lower rim of the central opening for preventing interference with the collar part of the center core disposed on a layer immediately below.