Drum cartridge having electrical contact surface positioned at outer surface of drum frame

An image forming apparatus comprising:

• a drum cartridge comprising:
• a photosensitive drum rotatable about an axis extending in a first direction;
• a drum frame having one end portion in a second direction at which the photosensitive drum is positioned;
• an electrical contact surface;
• and
• a holder positioned at an outer surface of the drum frame and movable in the second direction relative to the drum frame, the holder holding the electrical contact surface;
• a main body frame to which the drum cartridge is attachable;
• an electrical contact in contact with the electrical contact surface in a state where the drum cartridge is attached to the main body frame;
• and
• a belt unit configured to press the drum frame toward another side in the second direction in the state where the drum cartridge is attached to the main body frame.