A number of micro-sized rectangular dot-like n-type semiconductor regions 121 are created in a p-type semiconductor region which is a base body 11. Contact parts 14, each of which is in contact with one n-type semiconductor region 121 and almost entirely covers the same region, are mutually connected by a wire part 15 as a common cathode terminal. The n-type semiconductor regions 121 receives no light; their function is to collect carriers generated within and outside the surrounding depletion layers. Appropriate setting of the spacing of the n-type semiconductor regions 121 enables efficient collection of the carriers generated in the p-type semiconductor region while improving the SN ratio of the photo-detection signal by a noise-reduction effect due to a decrease in the p-n junction capacitance. Carriers originating from light of shorter wavelengths are barely reflected in the photo-detection signal. Thus, unfavorable influences of the shorter wavelengths of light are eliminated.