To provide a radio type human body detector not erroneously determining swinging of clothing inside a bathroom for a bathing person.

The human body detector is characterized by that it is provided with a human body detecting sensor picking up an image of a movement of a human body and processing the image, a bathroom drier installed in the bathroom and connected to a commercial power source, a radio type transmitter, a receiver having a signaling means issuing an alarm when an anomaly is detected by the human body detecting sensor, and a prohibiting means prohibiting monitoring action by the human body detecting sensor when the bathroom drier is driven.