A semiconductor light-receiving device includes: a first conduction layer of a first conduction type; a light absorption layer provided on the first conduction layer; a multiplication layer provided on the light absorption layer; a window layer provided on the multiplication layer, the window layer being undoped or having the first conduction type; and a second conduction region provided in the window layer by impurity diffusion, the second conduction region having a band gap wider than that of the light absorption layer and having a second conduction type different from the first conduction type. The following condition is satisfied: X/W≧(M−1)2/(2M) where W is a film thickness from a lower surface of the light absorption layer and an upper surface of the multiplication layer, X is a film thickness of the second conduction region, and M is a multiplication factor.