An apparatus is provided for fixing a shaft of a cartridge and an image forming device including the apparatus. The apparatus includes a fixed supporting part formed at a frame, and rotatably supporting a first end of at least one shaft of at least one cartridge. A movable supporting part is formed at the frame to be movable between a first position and a second position, and rotatably supporting a second end of the shaft of the cartridge. An operating part operates to move the movable supporting part between the first position and the second position. The fixed supporting part and the movable supporting part fix the shaft of the cartridge, and the movable supporting part works together with opening and closing operation of the cover. The shaft of the cartridge is fixed in the proper position, but also a corresponding cartridge, such as an image forming cartridges, is easily assembled and disassembled in the frame of the main body when the cartridge is mounted in the frame.