A wireless communication system, comprising: multiple wireless devices configured to perform wireless communication with each other by use of wireless signals propagating through an electric wave serving as a medium; each of the multiple wireless devices including: a transmitter configured to transmit a wireless signal; a receiver configured to receive a wireless signal; a power feeder configured to supply power to the transmitter and the receiver from a battery; a detector configured to periodically perform detection of occurrence of a predetermined event; and a controller configured to control the transmitter and the receiver; wherein the controller is configured to, when the detector has detected occurrence of the event, supply power from the power feeder to operate the transmitter intermittently so that the transmitter transmits a wireless signal corresponding to the predetermined event during a transmission period (Tq) in which the transmitter is in operation; wherein the controller is configured to repeat counting of a predetermined intermittent reception period (Tx); wherein the controller is configured to supply power from the power feeder to activate the receiver after completion of counting of the intermittent reception period (Tx), and to deactivate the receiver when the receiver fails to receive a predetermined wireless signal before expiration of a predetermined reception period from time at which the receiver is activated; wherein the controller is configured to synchronize a counting completion timing at which counting of a next intermittent reception period (Tx) is completed, with another wireless device; wherein each of the multiple wireless devices further includes an announcement device configured to make an audible announcement; wherein the controller is configured to, when the detector detects the occurrence of the event, control the announcement device to announce the occurrence of the event; and characterized in that the detector is configured to end the detection of occurrence of the event a predetermined time period (ΔT) earlier than the counting completion timing; and the controller is configured to control the transmitter to transmit a wireless signal corresponding to the event during the transmission period (Tq) when counting of a next intermittent reception period (Tx) is completed; wherein the predetermined time period (ΔT) is not shorter than an announcement time period necessary for the controller to control the announcement device to announce the occurrence of the event. multiple wireless devices configured to perform wireless communication with each other by use of wireless signals propagating through an electric wave serving as a medium; each of the multiple wireless devices including: a transmitter configured to transmit a wireless signal; a receiver configured to receive a wireless signal; a power feeder configured to supply power to the transmitter and the receiver from a battery; a detector configured to periodically perform detection of occurrence of a predetermined event; and a controller configured to control the transmitter and the receiver; a transmitter configured to transmit a wireless signal; a receiver configured to receive a wireless signal; a power feeder configured to supply power to the transmitter and the receiver from a battery; a detector configured to periodically perform detection of occurrence of a predetermined event; and a controller configured to control the transmitter and the receiver; wherein the controller is configured to, when the detector has detected occurrence of the event, supply power from the power feeder to operate the transmitter intermittently so that the transmitter transmits a wireless signal corresponding to the predetermined event during a transmission period (Tq) in which the transmitter is in operation; wherein the controller is configured to repeat counting of a predetermined intermittent reception period (Tx); wherein the controller is configured to supply power from the power feeder to activate the receiver after completion of counting of the intermittent reception period (Tx), and to deactivate the receiver when the receiver fails to receive a predetermined wireless signal before expiration of a predetermined reception period from time at which the receiver is activated; wherein the controller is configured to synchronize a counting completion timing at which counting of a next intermittent reception period (Tx) is completed, with another wireless device; wherein each of the multiple wireless devices further includes an announcement device configured to make an audible announcement; wherein the controller is configured to, when the detector detects the occurrence of the event, control the announcement device to announce the occurrence of the event; and characterized in that the detector is configured to end the detection of occurrence of the event a predetermined time period (ΔT) earlier than the counting completion timing; and the controller is configured to control the transmitter to transmit a wireless signal corresponding to the event during the transmission period (Tq) when counting of a next intermittent reception period (Tx) is completed; wherein the predetermined time period (ΔT) is not shorter than an announcement time period necessary for the controller to control the announcement device to announce the occurrence of the event.