First and second semiconductor lasers interelement-separated from each other are formed. Total thickness of a fourth upper cladding layer and a second contact layer of the second semiconductor laser is smaller than total thickness of a second upper cladding layer and the first contact layer of the first semiconductor laser. First and second ridges are formed in the first and second semiconductor lasers by dry etching, using a resist as a mask, and the dry etching is stopped when a second etching stopper layer is exposed at the second ridge. The second upper cladding layer remaining on a first etching stopper layer at the first ridge is selectively removed by wet etching, using the resist as a mask.