A transmission apparatus includes a plurality of output units and a detector. The plurality of output units is configured to couple to a plurality of transmission paths, respectively, branched from one transmission path. The plurality of output units includes at least one first output unit configured to transmit signal light selectively to one of the branched transmission paths, and at least one second output unit configured to transmit test light with a wavelength different from a wavelength of the signal light to another of the branched transmission paths. The detector is configured to decide a failure in the branched transmission paths, based on a result of detection of a reflected light of the test light received through at least one of the branched transmission paths.