An optical guide 43 is partly buried in a lens 43 on the diameter of its aperture, the lens 43 converging received light incident from the end face of an optical fiber onto a light receiving element 15 and the optical conductor 33 having a refractive index larger than that of the lens 43. The optical guide 33 is composed of a buried portion 33-1 and an extending portion 33-2, and transmitting light 22 incident on the optical guide 33 from the end face 33c of the extending portion 33-2 is reflected by a reflecting surface 33a and launched into the optical fiber. The transmitting light 22 is guided by the optical guide 33 to the end face of the optical fiber without leakage to the receiving-side portion.