A tire pneumatic pressure monitoring system contains tire pneumatic pressure monitoring receivers that receive radio signals transmitted from sensors and detect RSSI signals and pneumatic pressure data. A console processes the RSSI signals and the pneumatic pressure data and outputs indicating signals. An indicator indicates the tire pneumatic pressure with the indicating signals. The tire pneumatic pressure monitoring receivers are individually provided corresponding to the tires of a vehicle. The console is provided with a level adjusting unit for adjusting output levels of the RSSI signals by controlling the tire pneumatic pressure monitoring receivers. The levels of the respective RSSI signals input to the console from the respective tire pneumatic pressure monitoring receivers are set approximately equal.