A body movement detecting apparatus includes a time-frequency converting unit configured to convert an input acoustic signal to a frequency component, an electric power difference computing unit configured to compute an electric power difference value of the frequency component of each of predetermined frequency bandwidths, a duration computing unit configured to compute duration in which a number of the predetermined frequency bandwidths each exhibiting the electric power difference value less than a first threshold is equal to or greater than a second threshold, a similarity value computing unit configured to compute a value indicating similarity of the electric power difference value of each of the predetermined frequency bandwidths, and a body movement detecting unit configured to detect body movement based on the computed duration and the computed similarity value.
