An optical module includes a substrate, an optical device of a surface-emitting element or a surface-receiving element mounted on a surface of the substrate with a light-emitting portion or a light-receiving portion located to face the surface of the substrate, an optical fiber disposed parallel to the surface of the substrate and in a longitudinal direction of the substrate, a mirror provided to face the light-emitting portion or the light-receiving portion of the optical device and a tip of the optical fiber, and optically connect the optical device and the optical fiber, and an optical fiber receiving groove provided in the surface of the substrate to receive the optical fiber. A width of the mirror is greater than a width of the optical fiber receiving groove. Reflecting portions are provided on edges, respectively, of a mirror side end of the optical fiber receiving groove, and the reflecting portions reflect incident light from the mirror facing the edges, again back to the facing mirror.