An optical transmitting and receiving device enabling incident light from an exterior to be detected with high precision is provided. With an optical transmitting and receiving device 1, a groove 28, passing between an opening 22 and a pinhole 23 as viewed from a front and having both ends open to side surfaces of a light transmitting member 27, is formed in a front surface 27a of the light transmitting member 27, and a light blocking resin portion 3 reaches an interior of the groove 28. Thus, even if a portion of light emitted from an LD 9 undergoes multiple reflection inside the light transmitting member 27, the multiply reflected light is prevented by the light blocking resin portion 3 in the groove 28 from reaching a PD 12 as unwanted light. Detection of noise current due to the unwanted light can thereby be prevented and incident light from the exterior can be detected with high precision.