An image forming apparatus includes: a main body; a first cartridge; a second cartridge; and a retaining member. The main body includes a first power-supplying part; and a second power-supplying part. The first cartridge includes a first power-receiving part. The second cartridge includes a second power-receiving part. The first and second power-receiving parts are configured to contact with the first and second power-supplying parts respectively. The retaining member is configured to retain the first and second cartridges and includes one side wall having a frame formed of a resin material and a reinforcing member formed of a metal material. A top edge of the frame is positioned lower than top edges of the first and second power-receiving parts. A top edge of the reinforcing member is positioned at a same vertical position as or lower than the top edge of the frame.