To provide a wireless transmitter receiver which can transmit and receive wireless signals normally while preventing the wireless signals from interferring with each other.

When an infrared-ray signal reception part 31 receives a wireless signal sent from a wireless transmitter, a wireless receiver 3 generates a control signal for making and breaking a relay contact 34 by a control circuit 32 according to the wireless signal received by the reception part 31. The reception part 31 comprises an infrared-ray signal receiving circuit 31a which receives the wireless signal and a band-pass filter circuit 31b which passes only a specific frequency component in the signal received by the receiving circuit 31a and outputs it as a transmit signal to the control circuit 32. Here, the control circuit 32 outputs a switching signal to the band-pass filter circuit 31b according to the operation of a reception frequency changeover switch 36 to vary the center frequency of the band-pass filter circuit 31b.