After a light emitting element is mounted to a header of a light emitting lead frame, a light receiving element is mounted to a header of a light receiving lead frame and a power element is mounted to a header of a power lead frame, the light emitting element, the light receiving element and the power element are connected to respective lead portions with wires, and in a state with the light emitting element, and the light receiving element and the power element, disposed facing each other, they are entirely coated with a primary molding resin, and the primary molding resin and a heat sink formed in a heat dissipating lead frame are coated with a secondary molding resin. Also, a structure is adopted in which the lead terminal of the power element and the heat dissipating lead frame are stacked together, and joined at this stacked portion.