Detection of body motion of a subject in a bathroom is accurately performed. A body motion signal processing apparatus (100) includes: a transmission unit that transmits a radio wave to a target； a receiving unit that receives the radio wave reflected by the target； and a detection unit that detects, from a received signal received by the receiving unit, a body motion component signal corresponding to a body motion component that is motion of a body. The target includes a bathroom, and the body motion signal processing apparatus (100) further includes a signal processing unit (40) that, in a case where a subject is in the bathroom, compares amplitude of the body motion component signal detected by the detection unit to amplitude of the body motion component signal that is detected in advance in the bathroom where no subject exists, and outputs a notice based on a comparison result.
