A semiconductor device (1) includes a plurality of photodiodes (20) on a semiconductor substrate (11). Cathodes (22) and a common anode (21) of the plurality of photodiodes (20 (20a, 20b)) are formed so as to be electrically independent from the semiconductor substrate (11), the plurality of photodiodes (20) have the common anode (21) and the plurality of separate cathodes (22), and an output of the common anode (21) is considered to be equivalent to a sum of outputs of the plurality of separate photodiodes (20). Alternatively, the plurality of photodiodes have a common cathode and a plurality of separate anodes, and an output of the common cathode is considered to be equivalent to a sum of outputs of a plurality of separate photodiodes. By completely electrically isolating the anode and the cathode of the photodiodes from the substrate, the noise characteristic can be reduced, and crosstalk can be reduced.