A method and apparatus of image forming includes an optical writing device and an image carrier. The optical writing device includes a housing, a dustproof member, a light source, and a shield. The housing is provided with an opening. The dustproof member is light permeable and closes the opening. The light source is installed in the housing and irradiates the image carrier with a light beam through the dustproof member. The shield is movable between a first position to cover the dustproof member and a second position to uncover the dustproof member. The optical writing device also includes a cleaner attached to the shield and contact the dustproof member. The optical writing device also includes a driver for moving the shield. The optical writing device further includes a positioning mechanism for positioning the shield to the first position by using the driver.