A method for producing an integrated optical device includes the steps of growing a first stacked semiconductor layer including a first optical waveguiding layer, a first cladding layer, and a side-etching layer; etching the first stacked semiconductor layer through a first etching mask; growing, a second stacked semiconductor layer including a second optical waveguiding layer and a second cladding layer through the first etching mask; and forming a reverse-mesa ridge structure by etching the first and second cladding layers. The step of etching the first stacked semiconductor layer includes a step of forming an overhang by etching the side-etching layer by wet etching. In the step of growing the second stacked semiconductor layer, the second cladding layer is grown at a lower growth temperature and a higher V/III ratio comparing to those in the growth of the second optical waveguiding layer.