Wireless communications apparatus is provided by which power consumption is much more reduced in a wireless system composed of a base station and wireless terminal stations. The apparatus installed in the base station includes a transmitter/receiver and a controller. The transmitter/receiver compares an RSSI value indicating the received wave strength of a received wireless signal with a preset value periodically at time intervals set in a timer for defining a time to start and stop the controller. When the RSSI value indicates that the received wave strength is higher than the preset value, the controller is made operative, and then the demodulated received data of the received signal are sent to the controller. The controller operates when the preset value is set in the transmitter/receiver, and analyzes the received data when the received wave strength has exceeded the preset value.