A semiconductor light receiving element comprises a light absorption region formed in the vicinity of the main surface of the semiconductor substrate transparent to the incident light; an incident region set to be concentric with and larger than the light absorption region; and a partially spherical concave reflecting portion formed on a back surface of the semiconductor substrate and capable of reflecting incident light incident on the incident region from the main surface side toward the light absorbing region; wherein, when the radius of curvature of the portion is R, the diameter of the incident region is B, the distance between the light absorbing region and the concave reflecting portion is W, and the diameter of the light absorbing region is P, then the radius of curvature R satisfies a condition of 2 BW/(B−P/2)≤R≤2BW/(B−P).