An object of the present invention is to enable identification of a reflection signal from a terminal portion of an optical fiber to be measured where a reflection signal caused by multiple reflection appears in an OTDR waveform in a mode in which an OTDR and the optical fiber to be measured are connected at a bent portion. The reflection signal caused by multiple reflection inevitably propagates through a distance equal to a distance between true reflection points more than the other reflection point, because of multiple reflection. Therefore, a distance between the reflection signal and another reflection signal is inevitably coincident with a distance between the other reflection signals. In contrast, in a case of a reflection signal from a terminal portion of the optical fiber, the distance between the reflection signal and another reflection signal is not coincident with the distance between the other reflection signals.