Abstract: Ink cartridges 10a to 10d have different patterns from each other in positional relationship between projections 12a to 12d and insertion parts 16a to 16d, respectively, and cartridge holders 20a to 20d have different patterns from each other in positional relationship between slits 22a to 22d and ink introducing tubes 21a to 21d, as seen from the direction on which the ink cartridges 10a to 10d are mounted on the cartridge holders 20a to 20d, respectively. At the same time, the respective patterns of the positional relationships in the ink cartridges and the cartridge holders coincide with each other per each of the four colors of black, cyan, yellow and magenta. Thus, any one of ink cartridges is prevented from inadvertently joined to any one of the cartridge holders to which the ink cartridge does not correspond to.

Abstract: A developer cartridge including a frame, a developer carrying member, and an input gear member is provided. The frame includes a first side wall and a second side wall, and the first side wall and the second side wall extend in a length direction. The developer carrying member extends from the first side wall to the second side wall in a width direction perpendicular to the length direction. The developer carrying member includes a developer carrying member shaft rotatably supported by the first side wall and the second side wall, and the developer carrying member is rotatable about a first axis. The input gear member, for supplying a driving force for rotating the developer carrying member, is rotatably supported by the first side wall so as to be rotatable about a second axis. A first distance between the first axis and the second axis in the length direction is about 14.0 mm.