To provide a waveguide type optical integrated device in which large capacity and bidirectional optical communication is realized and to provide its manufacturing method.

A waveguide type optical integrated device 10 optically couples an optical waveguide section 10A which has a plurality of cores and an optical element section 10B which has a plurality of optical elements. The optical waveguide section 10A is provided with a plurality of cores 18 which are extended in a three dimensional manner and a clad which is extended around and along the cores 18 and has a refractive index that is smaller than the refractive index of the cores 18. The plurality of optical elements of the optical element section 10B is arranged with a pitch which is same as that of the core patterns of the cross section of the section 10A that is perpendicular to the extended direction of the cores 18. A groove section 12 is formed in the section 10A which includes the plurality of cores 18 so that the cross sections of the cores 18 are exposed and the optical element section 10B is mounted into the groove section 12 so that the plurality of optical elements and cores 18 are optically coupled.