PURPOSE: To provide an optical integrated device with an integration board, on which a high-efficiency dual-valance-type receiver, a high-efficiency semiconductor laser unit, and an optical waveguide are assembled in a well-matched way.

CONSTITUTION: An optical waveguide 421 is formed on a semi-insulating substrate 111 made of InP. On the InP substrate 111, an optical coupling element 424, a semiconductor laser 423, and a light receiving element 425 are integrated while they are connected with the optical waveguide 421. The optical waveguide 421, which is of semiconductor rib-type, is formed on an optical waveguide film made of laminated low-density semiconductor layers. Then, the semiconductor laser 423 and an active region 144d of the light-receiving element 425 are put selectively with a given width to the optical waveguide 421. A surrounding part of the active layer 114d is covered with a crystal layer that constitutes a rib with a smaller refractive index than that of the active region 114d. In this case, the optical waveguide 421, the optical coupling element 424, the semiconductor laser 423, and the light-receiving element 425 constitutes a mesa structure with a given width.