There is provided an optical package substrate and a molding method therefor, which provides for easy production, easy mounting of optical elements such as photodiodes and lasers, good functionality, productivity, and economy, as well as an optical device incorporating the package substrate. On the surface of an optical package substrate 11, a guide groove 12 used for the positioning of an optical fiber and a tapered face 13 adjoining the guide groove 12 are provided, the tapered face 13 being formed so as to have a predetermined angle. A mirror 17 for reflecting light is formed on the tapered face 13. An optical fiber 15 is affixed in the guide groove 12. Above the tapered face 13 is mounted a surface reception type photodiode 16, which is placed in a position for receiving light deflected by the mirror 17 provided on the tapered face 13. By providing a positioning marker (not shown) for a light receiving element on the optical package substrate 11, it becomes particularly easy to mount the surface reception type photodiode 16 through passive alignment.