A cartridge support unit includes a housing, a toner cartridge, a guide member, a shutter body, and at least one snap fit portion. The housing has an opening. The toner cartridge has a cylindrical shape, has an outer circumferential surface, and is removably mounted in the housing. The guide member has portions and is provided at such a position in the housing that the opening is interposed between the portions of the guide member. The shutter body slides against the guide member from a closed position where the shutter body covers the opening to an open position where the shutter body exposes the opening. The at least one snap fit portion extends from the shutter body and has a protrusion. The protrusion is pushed by the outer circumferential surface of the toner cartridge so as release a lock state at the closed position.