A variable capacitance device that includes a semiconductor substrate, a redistribution layer disposed on a surface of the semiconductor substrate, and a plurality of terminal electrodes including first and second input/output terminals, a ground terminal and a control voltage application terminal. Moreover, a variable capacitance element section is formed in the redistribution layer from a pair of capacitor electrodes connected to the first and second input/output terminals, respectively, and a ferroelectric thin film disposed between the capacitor electrodes. Further, an ESD protection element is connected between the one of the input/output terminals and the ground terminal is formed on the surface of the semiconductor substrate.