A wireless device, comprising: an interface module; and a wireless module, wherein the interface module includes: an interface which is connected to a field device and is configured to accept a first signal output from the field device; and a first local communications device which is configured to transmit the first signal to the wireless module by first local communications, wherein the wireless module includes: a second local communications device which is configured to receive the first signal from the first local communications device by the first local communications; a wireless communications device which is configured to wirelessly transmit the first signal to a first external device; and a first controller which is configured to set the interface module out of a sleep state, wherein the wireless communications device is configured to wirelessly receive a second signal destined for the field device from a second external device, the second local communications device is configured to transmit the second signal to the first local communications device by second local communications, and the interface is configured to output the second signal to the field device, wherein, when the wireless communications device of the wireless module wirelessly receives the second signal from the second external device, the first controller sets the interface module out of the sleep state, and then the second local communications device transmits the second signal to the interface module by the second local communications, when the interface module is set out of the sleep state by the first controller and the first local communications device receives the second signal from the wireless module, the interface module supplies power to the field device, and then the interface outputs the received second signal to the field device, when the interface of the interface module receives an input of data set as a command response from the field device, the interface module stops supplying the power to the field device, and then transmits the received command response to the wireless module, and the wireless communications device of the wireless module transmits the received command response to the second external device. an interface module; and a wireless module, wherein the interface module includes: an interface which is connected to a field device and is configured to accept a first signal output from the field device; and a first local communications device which is configured to transmit the first signal to the wireless module by first local communications, an interface which is connected to a field device and is configured to accept a first signal output from the field device; and a first local communications device which is configured to transmit the first signal to the wireless module by first local communications, wherein the wireless module includes: a second local communications device which is configured to receive the first signal from the first local communications device by the first local communications; a wireless communications device which is configured to wirelessly transmit the first signal to a first external device; and a first controller which is configured to set the interface module out of a sleep state, a second local communications device which is configured to receive the first signal from the first local communications device by the first local communications; a wireless communications device which is configured to wirelessly transmit the first signal to a first external device; and a first controller which is configured to set the interface module out of a sleep state, wherein the wireless communications device is configured to wirelessly receive a second signal destined for the field device from a second external device, the second local communications device is configured to transmit the second signal to the first local communications device by second local communications, and the interface is configured to output the second signal to the field device, wherein, when the wireless communications device of the wireless module wirelessly receives the second signal from the second external device, the first controller sets the interface module out of the sleep state, and then the second local communications device transmits the second signal to the interface module by the second local communications, when the interface module is set out of the sleep state by the first controller and the first local communications device receives the second signal from the wireless module, the interface module supplies power to the field device, and then the interface outputs the received second signal to the field device, when the interface of the interface module receives an input of data set as a command response from the field device, the interface module stops supplying the power to the field device, and then transmits the received command response to the wireless module, and the wireless communications device of the wireless module transmits the received command response to the second external device.