False determination in the presence or absence of a person in a in a room is limited. An air conditioner suspends an air conditioning operation if a room is vacant. If at least one of motion detectors, each provided to one of the indoor units, starts to detect the presence of a person during suspension of the air conditioning operation, an indoor controller of an indoor unit sums, for each of the motion detectors, time periods in which the presence of the person is detected to obtain a detection time period sum. If any one of detection time period sums, each for one of the motion detectors, reaches a reference value within a predetermined time period, the outdoor controller causes the air conditioner to resume the air conditioning operation.