PURPOSE: To perform communication by reducing the influence of an interference wave even when it exists in a frequency band in radio communications equipment which performs the communication in a predetermined frequency band.

CONSTITUTION: The presence/absence of the interference wave in the predetermined frequency band is detected by an interference wave detection circuit 7 on a transmission side, and when it exists, a frequency synthesizer 10 is controlled by the output of the circuit, and the frequency of a local oscillation signal is varied, and the center frequency of a transmission signal is shifted. A frequency component appearing outside the frequency band can be eliminated by such shift by a notch filter 4. The frequency of the local oscillation signal can be varired also on a reception side by the similar procedure, and reception is performed, thereby, the influence of the interference wave can be reduced.