To prevent fluctuation in element performance by reducing light loss and current leak in an MMI type semiconductor laser wherein a multimode waveguide which is wider than a basic mode waveguide is connected to the basic mode waveguide.

A laminated film comprising an active layer and a clad layer is formed on a substrate. A mesa part comprising a basic mode waveguide 102 and a multimode wavegudie 104 is formed by selectively removing the clad layer and the active layer. A semiconductor layer is formed to bury a periphery of the mesa part. An end face of the multimode waveguide tilts to surfaces which are equivalent to a (100) surface or a vertical line of a substrate surface to the surfaces, and the mesa part is shaped to include a surface with an off angle less than 7 degree to a substrate surface direction.