An optical communication module includes a base substrate; a wavelength branching filter arranged on the base substrate, in which a light is allowed to go through or be reflected according to a wavelength thereof; a photodetector arranged on the base substrate to receive a light passed through the wavelength branching filter and to convert the light into an electric signal; and a light emitting device arranged on the base substrate to provide a transmission light. The transmission light is outputted through the wavelength branching filter. The optical detector comprises a light receiving portion which is formed to have a first length and a second length, which is shorter than the first length. The first length of the light receiving portion is perpendicular to an optical axis of an input light on a plane parallel to a surface of the substrate, and a second length of the light receiving portion is parallel to the optical axis of the input light.