The light sensor according to an exemplary embodiment of the present invention is a multi-function light sensor that is equipped at low cost with both an ultraviolet light sensor and a visible light sensor and suppresses leak current between adjacent elements on the same substrate. The light sensor is equipped with a SOI substrate, formed from a silicon oxide insulating film and a silicon semiconductor layer made up from single crystal silicon, on a silicon substrate. Photodiodes PD1 and PD2 are formed on the silicon substrate, and a photodiode UV-PD, and main portions (source, drain and channel regions) of a MOSFET configuring a control circuit, are formed in the silicon semiconductor layer on the insulating film.