ANOMALY DETECTION APPARATUS, METHOD, SYSTEM AND PROGRAM

An abnormality detection device includes: a vibration acquisition unit configured to acquire an acoustic signal generated during passage of a vehicle on a road; a frequency domain conversion unit configured to convert the acquired acoustic signal into a frequency domain signal; an unexpectedness determination unit configured to determine whether there is unexpectedness at each predetermined frequency using the frequency domain signal; and an abnormality determination unit configured to determine whether there is an abnormality in the road based on the number of frequencies at which it is determined that there is the unexpectedness.