A capacitor device includes a substrate including a first well having a first conductivity type and a first voltage applied thereto and a second well having a second conductivity type and a second voltage applied thereto; and a gate electrode disposed on an upper portion of the first well or an upper portion of the second well in such a way that the gate electrode is insulated from the first well or the second well, wherein capacitances of the capacitor device include a first capacitance between the first well and the second well and a second capacitance between the first well or the second well and the gate electrode.