Provided is a photodetection device which is small in size and has excellent sensitivity. The photodetection device (10) puts cathode terminals of photodiodes (1 and 2) having different spectral characteristics, or a photodiode (1) provided with an optical filter and a photodiode (2) provided with a light shield layer, into an open end state, and detects light intensity of a desired wavelength region according to a difference in electric charges that have been stored in those photodiodes in a given period of time. Since the photodiodes 1 and 2 store electric charges, even if a photocurrent is small, it is possible to store the photocurrent to obtain the electric charges required for detection, permitting achievement of downsizing and high detection performance of the semiconductor device on which the photodiodes 1 and 2 are formed. It is also possible to realize a wide dynamic range by making the electric charge storage time variable according to the light intensity, to suppress electric power consumption by intermittently driving an element required for differential detection at the time of differential detection, and to reduce an effect from flicker by averaging the output.