Abstract: A transmission optical signal emitted from a laser diode is introduced in an S-polarized state to a polarization-reflection film formed on an inclined surface of a prism. This transmission optical signal is in a light quantity that is reflected by the polarization-reflection film to enter an optical fiber. With this configuration, an optical transmission-reception apparatus for a single-core bi-directional optical communication circuit enables an enhancement of the efficiency of introduction of the transmission optical signal into the optical fiber constituting the optical communication circuit so that a sufficient performance and reliability of the optical communication circuit is realized without increasing the light quantity emitted from the laser diode which outputs the transmission optical signal.