An occupancy detection apparatus has a switch, a first antenna, a second antenna, a transmitter, and a motion detection circuit. The occupancy detection apparatus monitors for a first motion in a first region using the first antenna using a first motion detection parameter. When no first motion is sensed by the monitoring using the first antenna, the occupancy detection apparatus monitors for a second motion in a second region using the second antenna using a second motion detection parameter. When no second motion is sensed by monitoring using the second antenna, the occupancy detection apparatus designates a space, which encompasses the second region, as unoccupied. The first region and the second region overlap one another, and the first motion detection parameter is different from the second motion detection parameter.