Inspection apparatus for optical transmission device

An inspection apparatus for an optical transmission device comprises a coupling means to be optically coupled to an optical transmission device, a selecting means for optically separating and selecting an optical signal of a specific wavelength from a plurality of optical signals having different wavelengths transmitted from the optical transmission device, a converting means for converting the selected optical signal into an electrical signal, and a displaying means for displaying the selected wavelength according to the electrical signal. The wavelength of a transmission signal from the optical transmission device can be easily and visually checked by selecting a signal of a specific wavelength out of a plurality of signals having different wavelengths transmitted from the transmission device, and by displaying the selected wavelength by the displaying means. Thus, an optical transmission device used for single-optical-fiber bidirectional transmission can be easily checked as to whether it is provided for a subscriber or for a central station.