In an image forming device, a Light Emitting Diode (LED) head is attached to a slide member. The slide member includes a slidable base side member and a leading end side member which can move with respect to the base side member in a direction that is different from a sliding direction of the base side member. The LED head is provided on the leading end side member, and a positioning pin is provided on the LED head. The LED head is positioned with respect to a photoconductive drum by the positioning pin.