An event recognition apparatus is configured to acquire an observation signal indicating sound or vibration that occurs at a point along an optical fiber and is detected by optical fiber sensing, also acquire a noise signal indicating optical noise present at a point along the optical fiber, and by using statistical information of a sound signal or a vibration signal acquired by a sound sensor or a vibration sensor, derive, from each of the observation signal and the noise signal, a posterior probability that at least one event occurs at a point along the optical fiber, and compare a posterior probability derived from the observation signal with a posterior probability derived from the noise signal, derive, from a result of the comparison, a posterior probability that the at least one event occurs at a point along the optical fiber, and output a result of the derivation.