An image forming device includes a main frame of the image forming device having a body, a drum shaft which is positioned and supported by the body of the main frame of the image forming device, a photoconductive drum which is provided removably in the main frame of the image forming device and supported rotatably on the drum shaft, and an optical writing head which includes positioning pins and is positioned relatively with respect to the photoconductive drum. By contacting the positioning pins against a circumferential body of the drum shaft, the optical writing head is positioned relatively with respect to the photoconductive drum.