A high frequency switch module for switching frequency bands, comprising: an antenna port connected to an antenna; a plurality of transmission signal ports (3,4) for receiving transmission signals at each of a plurality of frequency bands; a plurality of reception signal ports (5,6) for outputting reception signals at each of a plurality of frequency bands; a high frequency switch including a semiconductor switch element and adapted to selectively connect one signal port, among the transmission signal ports (3,4) and the reception signal ports (5,6), to the antenna port; a plurality of low-pass filters (30,40), each provided between the high frequency switch and each of the transmission signal ports (3,4), and configured to allow a transmission signal input to each of the transmission signal ports (3,4) to pass therethrough and to intercept a harmonic resulting from the transmission signal; and a plurality of phase adjusting lines (16,17) for connecting the high frequency switch to the respective low-pass filters (30,40), wherein the length of each of the phase adjusting lines (16,17) is adapted to adjust a phase difference between a progressive wave of a harmonic of at least one frequency resulting from the transmission signal and produced at the high frequency switch and a reflected wave resulting from reflection of the progressive wave from one of the low-pass filters (30,40), with regard to each of a second harmonic and a third harmonic, respectively, wherein said phase difference is such that, at a point of the high frequency switch, each of a composite wave made up of the progressive wave and the reflected wave, with regard to the second harmonic and the third harmonic, respectively, has a lower power as compared to a case where the phase difference between the progressive wave and the reflected wave is zero. an antenna port connected to an antenna; a plurality of transmission signal ports (3,4) for receiving transmission signals at each of a plurality of frequency bands; a plurality of reception signal ports (5,6) for outputting reception signals at each of a plurality of frequency bands; a high frequency switch including a semiconductor switch element and adapted to selectively connect one signal port, among the transmission signal ports (3,4) and the reception signal ports (5,6), to the antenna port; a plurality of low-pass filters (30,40), each provided between the high frequency switch and each of the transmission signal ports (3,4), and configured to allow a transmission signal input to each of the transmission signal ports (3,4) to pass therethrough and to intercept a harmonic resulting from the transmission signal; and a plurality of phase adjusting lines (16,17) for connecting the high frequency switch to the respective low-pass filters (30,40), wherein the length of each of the phase adjusting lines (16,17) is adapted to adjust a phase difference between a progressive wave of a harmonic of at least one frequency resulting from the transmission signal and produced at the high frequency switch and a reflected wave resulting from reflection of the progressive wave from one of the low-pass filters (30,40), with regard to each of a second harmonic and a third harmonic, respectively, wherein said phase difference is such that, at a point of the high frequency switch, each of a composite wave made up of the progressive wave and the reflected wave, with regard to the second harmonic and the third harmonic, respectively, has a lower power as compared to a case where the phase difference between the progressive wave and the reflected wave is zero.