To provide a fixing method of optical passive parts of a low cost which have high fixing strength of optical elements to each other and do not affect the characteristics of the optical elements.

The optical passive parts formed by bonding the at least ≥2 optical elements are provided with adhesive layers only in the circumferences of light transparent parts of light beams between the respective optical elements. Even more, the optical elements are bonded to each other by inserting adhesive sheets between at least the ≥2 optical elements and curing the adhesive sheets while press bonding the entire part.