Abstract: An LED array chip comprising; a first semiconductor layer having p-type conduction; a second semiconductor layer having a n-type conduction, possessing forbidden band width smaller than the first layer and provided on the first layer, so as to form a semiconductor chip having a pn junction at the interface with the first layer; the second layer being divided into a first region and a second region by etching the second layer through to the pn junction, the first region thereof being divided to form individual plural LEDs of predetermined configuration, and the n-type layer in the second region being converted to the p-type layer as so to serve as a common region; individual electrodes respectively provided to the surfaces of the LEDs; and a common electrode provided to the common region, parts of the exposed surface of the p-type layer corresponding to the LEDs serving as light emitting surfaces.