A drum cartridge including a photosensitive drum, a drum frame configured to retain the photosensitive drum and to accept a developing cartridge including a toner memory, which stores information concerning the developing cartridge, a first connector electrically connectable with the toner memory in the developing cartridge under a condition where the developing cartridge is attached to the drum frame, a relay board electrically connectable with the first connector, a second connector electrically connectable with a connector in an image forming apparatus and with the toner memory through the relay board, and a thermistor electrically connectable with the relay board, is provided.