A wireless speaker, which is configured to communicate with a controller and to reproduce and output an audio signal in accordance with remote operation performed on the controller, the wireless speaker comprising: output characteristic measurement means for sequentially measuring output characteristics of audio signals that are output within a predetermined period, wherein the output characteristic measurement means is configured to sequentially measure, as the output characteristic, output volume levels of audio signals that are output within the predetermined period from the wireless speaker; input characteristic reception means for sequentially receiving, from the controller, input characteristics of audio signals that are input within the predetermined period to a microphone, which is included in the controller, wherein the input characteristic reception unit is configured to sequentially receive, as the input characteristic, input volume levels of audio signals that are input within the predetermined period to the microphone included in the controller; determination means for comparing the latest output characteristic measured by the output characteristic measurement means and the latest input characteristic received by the input characteristic reception means, wherein the determination means is configured to determine that the listener is away from the vicinity of the wireless speaker when a ratio of the latest input volume level received by the input characteristic reception means to the latest output volume level measured by the output characteristic measurement means drops by a predetermined value or more; and control means for stopping output of an audio signal when the determination means determines that the listener is away from the vicinity of the wireless speaker. output characteristic measurement means for sequentially measuring output characteristics of audio signals that are output within a predetermined period, wherein the output characteristic measurement means is configured to sequentially measure, as the output characteristic, output volume levels of audio signals that are output within the predetermined period from the wireless speaker; input characteristic reception means for sequentially receiving, from the controller, input characteristics of audio signals that are input within the predetermined period to a microphone, which is included in the controller, wherein the input characteristic reception unit is configured to sequentially receive, as the input characteristic, input volume levels of audio signals that are input within the predetermined period to the microphone included in the controller; determination means for comparing the latest output characteristic measured by the output characteristic measurement means and the latest input characteristic received by the input characteristic reception means, wherein the determination means is configured to determine that the listener is away from the vicinity of the wireless speaker when a ratio of the latest input volume level received by the input characteristic reception means to the latest output volume level measured by the output characteristic measurement means drops by a predetermined value or more; and control means for stopping output of an audio signal when the determination means determines that the listener is away from the vicinity of the wireless speaker.