it is an object of the invention to provide a led write apparatus wherein the arrangement step of led chips is eliminated by constituting the led head by a single led chip composed of leds and electrical connection of the respective leds with driving circuits is carried out with ease . a led head chip is constituted in such a manner that 2400 leds in all whose width a is selected to be narrow , namely about 10 μm are formed on a si substrate having a smaller width than that of a photosensitive drum through a gaas substrate and as well peripheral circuits including a driving circuit such as a transistor are integratedly formed on the si substrate . the light from the led head chip is magnified via a lens to form an image on the photosensitive drum .