A semiconductor laser of an embodiment includes: an optical resonator having a first cladding layer, a ring-shaped active layer on the first cladding layer, a ring-shaped second cladding layer on the active layer, a first electrode inside the ring shape on the first cladding layer, a ring-shaped second electrode on the second cladding layer, a first insulating layer between the first cladding layer and the active layer, formed from an inside wall toward an outside wall of the ring shape, where an outside wall side edge thereof is on an inner side than the outside wall, and a second insulating layer between the active layer and the second cladding layer, formed from the inside wall toward the outside wall, where an outside wall side edge thereof is on an inner side than the outside wall; and an optical waveguide optically coupled to the optical resonator.