An optical coupling element for optically coupling an optical element formed on a substrate to an external optical element disposed adjacent to the substrate, including a first optical waveguide section formed on the substrate and having a smaller width on the side of the external optical element than a width on the side of the optical element, and a second optical waveguide section formed on the substrate and connected to the first optical waveguide section on the side of the external optical element, and having a smaller width on the side of the external optical element than a width on the side of the optical element and having a shorter length than a length corresponding to twenty wavelengths of the optical signal. The optical waveguide section can optimize the optical coupling efficiency, and the optical waveguide section can suppress residual reflections.