A quality measuring section measures reception quality of a radio signal received by a wireless communication section. A quality information transmitting section transmits reception quality information indicating the reception quality measured by the quality measuring section. A device number calculating section calculates, based on reception quality indicated by reception quality information transmitted from other wireless communication devices and the reception quality measured by the quality measuring section, the number of wireless communication devices, from among the other wireless communication devices, that can communicate with the wireless communication device including this device number calculating section. A power value determining section compares the number of the wireless communication devices calculated by the device number calculating section with a predetermined number of devices, to determine, on the basis of the comparison result, a transmission power value for the wireless communication section to transmit the radio signal.