A transmission-reception device includes an antenna duplexer, an antenna, and first and second transmission-reception circuits. A demultiplexer is connected between the first transmission-reception circuit and the antenna duplexer, and a multiplexer is connected between the second transmission-reception circuit and the antenna duplexer. A signal adjusting unit is connected between the demultiplexer and the multiplexer. The amplitude and phase of a third harmonic signal of a first transmission signal reflected by the antenna are detected. The signal adjusting unit adjusts the amplitude and phase of the third harmonic signal demultiplexed by the demultiplexer on the basis of the detection results, and outputs a cancel signal. The multiplexer synthesizes and hence cancels the third harmonic signal reflected by the antenna and the cancel signal with each other.