An ultraviolet sensor has an ultraviolet detection diode having a depletion region 18 formed in an Si layer 16 on an insulating layer 14, an interlayer insulating film 20 formed on the ultraviolet detection diode, and a wiring 24 formed on the interlayer insulating film 20. An incident angle θ (°) of an incident light entering into the depletion region 18 and a film thickness Tsi (nm) of the depletion region 18 satisfy the following formula (1), which is also shown in FIG. 14. TSi≦TSi/sin θ≦100   (Formula 1)