To shorten time required for mounting a light-receiving element supporting carrier and to mount parts with high density by forming a recessed part whose positioning reference is common with a light transmission part on a silicon substrate and engaging the carrier having the light-receiving element with the recessed part.

An optical module 11 positions an etching mask by using a mark 21 becoming the positioning reference when a quartz glass optical waveguide 13 is formed and forms the recessed part 18. Since the recessed part is positioned against the quartz glass optical waveguide 13, the optical axis of the light-receiving element 17 is matched with that of a branching path 15a by engaging the carrier 14 into the recessed part 18. Since a part of the silicon substrate 12 is recessed and formed, the position is prevented from being shifted even if the carrier 14 collides with the substrate at the time of mounting. Since the optical axis of the light-receiving element 17 and that of the branching path 15a are matched even if the carrier 14 is not moved on the silicon substrate 12, a space where the carrier 14 moves is not necessary to be formed.