A semiconductor antenna switch has an antenna terminal, a transmission terminal and a reception terminal. The antenna switch is capable of reducing harmonic distortion even though it includes field effect transistors formed over a silicon substrate. A shunt transistor including a plurality of series-connected field effect transistors is connected between he transmission terminal and a common terminal, such as a common terminal, which may be an electrical ground. Off capacitances and/or gate widths of a plurality of the series-connected field effect transistors increase monotonically in the direction from the common terminal to the transmission terminal, or equivalently, decrease monotonically in the direction from the transmission terminal to the common terminal.