To achieve the power saving of a network relay device by suppressing the consumption of the stand-by power of the network relay device.

An Ethernet converter 10 is provided with: an LAN switch 130 as a wired communication unit for communicating with wired network devices; an RF device 140 and an antenna 150 as a wireless communication unit for communicating with wireless network devices; a wired device monitoring portion 102 for monitoring the operating state of the wired network devices via the LAN switch 130; and an RF device controller 106 for controlling the operation of the RF device 140 based on the operating state of the wired network devices. When it is determined that the wired network device is not operating as the result of monitoring by the wired device monitoring portion 102, the wireless device controller 106 stops the operation of the RF device 140 so that the power consumption of the RF device 140 can be made smaller than that when the wired network devices are operating.