An antenna switching method of a wireless communication system capable of efficiently transmitting various signals from a plurality of transmitting antennas to a receiving unit is provided. The method includes a received signal intensity measuring step of operating an antenna switch (23) and obtaining received signal intensities of all the transmitting antennas (24, 25), a step of comparing the obtained received signal intensities of all the transmitting antennas and determining a transmitting antenna wherein the received signal intensity is the highest, a step of operating the antenna switch so that the transmitting antenna wherein the received signal intensity is the highest is connected to a transmitting circuit 22 and fixing the transmitting antenna, and a step of transmitting signals thereafter from the transmitting circuit via the fixed transmitting antenna.