A variable capacitance capacitor has a plurality of variable capacitance elements, using a thin-film dielectric layer whose dielectric constant varies with voltage application, connected in series with one another between the high-frequency signal input and output terminals. The first bias lines belonging to a high-potential side and the second bias lines belonging to a low-potential side, in terms of voltage application, are connected, alternately, to electrodes of the variable capacitance elements connected one another and electrodes in the array of the series-connected variable capacitance elements connected respectively to the input terminal and the output terminal.