To provide an optical coupling device and a mounting method thereof that allow loss of an amount of light to be restrained.

In an optical coupling device 1, when an optical fiber holder 10 for holding an optical fiber 11 is joined with a wavelength conversion member holder 30 for holding a wavelength conversion member 33 composed of a fluorescent body 31 and an optical characteristic matching member 32, the optical fiber 11 is joined with the wavelength conversion member 33 by optical coupling. The optical coupling device 1 includes: a region 71 which is, when both the holders 10 and 30 are joined together, formed on both an end surface 11b of the optical fiber 11 and an end surface 32b of the wavelength conversion member 33 joined by the optical coupling, and in which foreign matter 3 for shading a laser beam transmitted through the optical fiber 11 to be incident on the wavelength conversion member 33 is removed from an optical axis 11a of the optical fiber 11 and an optical axis 33a of the wavelength conversion member 33; and a region 72 which is formed at the outside of the region 71 when both the holders 10 and 30 are joined together, and into which the foreign matter 3 removed from the region 71 flows.