An optical package substrate and a molding method therefor which provide for easy production, easy mounting of optical elements such as photodiodes and lasers, good functionality, productivity and economy, and an optical device incorporating the package substrate. On the surface of an optical package substrate, a guide groove used for the positioning of an optical fiber and a tapered face adjoining the guide groove are provided, the tapered face being formed to have a predetermined angle. A mirror for reflecting light is formed on the tapered face. An optical fiber is affixed in the guide groove. A surface reception type photodiode, which is placed in a position for receiving light deflected by the mirror, is mounted above the tapered face. By providing a positioning marker for a light receiving element on the optical package substrate, it becomes particularly easy to mount the surface reception type photodiode through passive alignment.