An optical module includes: a transparent substrate through which light can pass; a photoelectric conversion element mounted on the transparent substrate and emitting light toward the transparent substrate or receiving light having passed through the transparent substrate; and a support member supporting an optical fiber for transmitting light, the support member and the transparent substrate forming an optical path between the photoelectric conversion element and the optical fiber. A positioning hole is formed in the transparent substrate. A positioning pin having a tapered surface is formed on the support member. The transparent substrate and the support member are positioned with respect to one another by inserting the positioning pin into the positioning hole along the optical axis direction of light between the transparent substrate and the support member and by making the tapered surface of the positioning pin contact the edge of the positioning hole without leaving any space therebetween.