An image forming apparatus includes a main body, a drum cartridge removably attached to the main body, and a belt unit removably attached to the main body. The main body includes a drum power supply, a belt power supply, and a controller configured to start supplying power from the drum power supply to a drum memory of the drum cartridge, start supplying power from the belt power supply to a belt memory of the belt unit, stop supplying the power from the drum power supply to the drum memory after starting supplying the power from the drum power supply to the drum memory, and stop supplying the power from the belt power supply to the belt memory after starting supplying the power from the belt power supply to the belt memory.