An optical transmission and receiving module includes a light source; a light receiving element; and a light branching element for causing signal light from the light source to be incident on an optical fiber and causing signal light output from the optical fiber to be incident on the light receiving element. The light branching element includes a prism array including a plurality of triangular prisms arranged at substantially an identical pitch on a plane extending substantially perpendicular to an imaginary line connecting the light source and the light receiving element.