Provided is a communication system achieving favorable beamforming training even in an environment where multiple wireless communication networks adjacently exist. In this communication system, in an RXSS, an STA measures received signal qualities of respective first training frames received from an AP and ranks the received signal qualities. In a TXSS following the RXSS, the STA measures received signal qualities of respective third training frames received from the AP and ranks the received signal qualities. The STA transmits fourth training frames respectively including the measured received signal qualities of the third training frames based on the ranks of the received signal qualities of the first training frames.