An image forming device includes a photoconductive drum that is removably provided in a main frame. An optical writing head includes positioning pins and is positioned relatively to the photoconductive drum. A paper guide member includes positioned parts and is fixed in proximity to the photoconductive drum and at a proper relative positional relationship with respect to the photoconductive drum. The paper guide member is formed of a metal plate material and is fixed integrally on the main frame body via attachment bases at both sides of the paper guide member. By the positioning pins being caught in the positioned parts, the optical writing head is positioned relatively with respect to the photoconductive drum.