An image forming apparatus includes a casing; an endless belt; a cleaning unit configured to collect a waste toner remaining on the endless belt; a first cartridge including a first accommodating portion to accommodate toner to be supplied to a first photosensitive member; a second cartridge including a second accommodating portion to accommodate toner to be supplied to a second photosensitive member, and a waste toner retainer to accommodate waste toner collected by the cleaning unit; a waste toner conveying unit configured to convey the waste toner collected by the cleaning unit to the waste toner retainer; and a moving member configured to support the first cartridge, the second cartridge, and the cleaning unit, the moving member being movable in a first direction from an inner position in the casing to an outer position out of the casing. The second cartridge is positioned at an upper stream position than a position of the first cartridge in the first direction when the moving member supports the first cartridge, the second cartridge, and the cleaning unit. And, the cleaning unit is positioned at a lower stream position than a position of the first cartridge when the moving member supports the first cartridge, the second cartridge, and the cleaning unit.