Optical transmission monitoring apparatus

An optical transmission monitoring apparatus provided with a structure for determining, at an early stage, the cause of a transmission abnormality that has occurred in the propagation path of an optical signal. The optical transmission monitoring apparatus (2A) is an apparatus which propagates an optical test pulse from a first station (11n) side to a second station (12n) side in an optical fiber transmission path (13n), and monitors the optical transmission according to the backscattered light generated in that propagation. The optical transmission monitoring apparatus (2A) is provided with an optical switch (20), a measurement apparatus (30), and an optical transmission abnormality determining apparatus (50). The optical transmission abnormality determining apparatus (50) includes an optical transmission monitoring unit (51), a measurement control unit (52), an optical transmission path testing unit (53), a test data management unit (54), a wiring information management unit (55), an optical switch wiring i