A semiconductor switch circuit includes a switch between an input node and an output node that connects nodes to each other according to a control signal and a level shifter outputting the control signal at a boosted level that is greater than a power supply voltage level. The semiconductor switch circuit also includes a booster circuit to output a boosted voltage at the boosted level higher than a power supply voltage level. A control circuit is configured to control the level shifter output of the control signal to the switch. A capacitance switching circuit is included to change the capacitance of a connection between the booster circuit and the level shifter. The capacitance switching circuit can vary capacitance according to the voltage level of the booster circuit output.