An anomaly detection apparatus estimates time series data of a first signal of each appliance by disaggregating an aggregate signal that is a sum of first signals of a plurality of appliances into each first signal of an individual appliance, calculates a residual by subtracting sum of the estimated first signals of the plurality of appliances from the aggregate signal, and obtains value of the second signal at a time point at which the residual indicates presence of anomaly, and checks if there is match of pair of value of the estimated first signal and estimated state of the appliance, with any one of the one or more pairs of value of the first signal and state of the appliance, stored in a table, in association with the value of the second signal at the time point at which the residual indicates presence of anomaly to identify appliance with anomaly.