PURPOSE: To obtain a computer radiographing cassette with simple structure where a photographic element is attached and detached without necessitating a special device.

CONSTITUTION: A cassette 20 is provided with an upper part 22 and a lower part 24 forming the cassette by being combined nest insert system. The upper part 22 has a rectangular panel and edge part walls 32, 34 and 36 extended in the periphery of three side edge parts of the panel. The lower part 24 is provided with the rectangular panel where the photographic element is permanently fixed. The edge part wall 60 is attached at only one side edge part of the rectangular panel of the lower part 24. The edge part wall 60 is extended in between the edge part walls 32 and 34 of the upper part when both parts 22 and 24 are assembled. Though both parts are held in an assembled state by a latch mechanism, the latch mechanism is easily released by an actuator. Thus, the photographic element is easily supplied to a computer radiographic reader as well as the lower part 24.