To enhance adhesion of a translucent body formed of translucent resin to a light shielding body, which is formed of light shielding resin and located in a recess provided to the translucent body.

A light emission side wiring 1 and a light receiving side wiring 2 are formed on a board 3, a light emitting element 4 is connected to the light emission side wiring 1, the photodetecting element 5 is connected to the light receiving side wiring 2, the elements 4 and 5 are integrally sealed up with molding resin, and thus a translucent body 6 provided with a recess 9 located an intermediate point between the elements 4 and 5 can be obtained. A through- hole 12 is provided to the base 11 of the translucent body 6, a filling hole 13 is provided to the board 3 for communicating with the through-hole 12, and light shielding resin is filled into the recess 9 and the holes 12 and 13, by injection molding to form a light shielding body 7 which isolates the elements 4 and 5 from each other. The translucent body 6 and the board 3 are increased in close contact area with the light shielding body 7, so that the light shielding body 7 will not comes off the translucent body 6.