A holder unit is configured to hold a plurality of photosensitive drums such that the plurality of photosensitive drums are arrayed in a predetermined direction and juxtaposed with each other with a space between neighboring photosensitive drums. A plurality of developing units is held by the holder unit, each is provided in association with each photosensitive drum, and each includes a developing roller displaceable between a contact position where the developing roller is in contact with the photosensitive drum and a spaced position where the developing roller is spaced away from the photosensitive drum. A spacer member has a plurality of retaining portions each in association with each developing unit and configured to retain each developing unit at the spaced position, and a linking portion integral with the retaining portions and configured to connect neighboring retaining portions therethrough in the predetermined direction.