A head moving mechanism includes a head connecting member, a contact member, and a linking mechanism. An LED array head is attached to the head connecting member. The contact member is movable in the vertical direction, and the linking mechanism moves the head connecting member in the vertical direction in association with the vertical movement of the contact member. When a process cartridge is mounted to a main casing, the contact member contacts the process cartridge and moves upward. This moves the LED array head toward a photosensitive drum. On the other hand, when the process cartridge is pulled out from the main casing, the contact member moves downward, moving the LED array head away from the photosensitive drum.