PURPOSE: To obtain photo receiving transistors which can sufficiently deal with high resolution by a method wherein two main electrode regions consisting of regions having conductivity types different from each other are made adjacent to two control electrode regions, regions having conductivity types respectively different, via high resistant region, and then holes and electrons of electron- hole pairs generated by photo excitation are separately accumulated to the control electrode regions.

CONSTITUTION: An n- type layer 5 is epitaxially grown on an n+ type Si substrate 1 and then formed into island form by means of an SiO2 film 4 for element isolation, where the p type base region 6 of a bipolar transistor put in floating state is formed, and an n+ emitter region 7 is provided therein. Next, the entire surface is covered with an SiO2 film 3, a window being opened, and an Al wiring 8 being formed, and an electrode 9 supplying pulses to the region 6 is provided on the region 6 via film 3. Thereafter, a collector electrode 12 is adhered to the back surface of the substrate 1 via n+ layer 11, and electrons of the electron-hole pairs generated by a light 20 incident to the surface are accumulated to the substrate 1, and holes to the region 6, respectively.