A structure in which a shutter is moved in a first direction by a motor, an opening is provided in the shutter, and the shutter is moved in a second direction using an elastic force of a spring connected to an upper cover of a light scanning device and an inside wall at the opening of the shutter increases the size of the structure of the shutter and the structure of the light scanning device due to the position of the spring. Therefore, a recess is provided in an opposing surface of a cover opposing a shutter, and a spring for sliding the shutter is connected to a connection portion provided at the recess. The recess is provided at a side opposite to the light source units with a polygon mirror being interposed therebetween.