To provide a voltage controlled variable capacitor that can be its manufactured without changing the conventional manufacture process, or adding any new process, preventing the circuit from being largely scaled or integrated into a high voltage, preventing the maximum value and minimum value of the capacitance per the unit area of an electrode from being fluctuated, and arbitrarily selecting high frequency C-V characteristics.

The surface of a p-type substrate 1 is formed with varactor elements 13 and 14. In the varactor element 13, the surface of the p-type substrate 1 is formed with an N well 2, and a gate insulating film 6 is formed on the N well 2, and an n-type polysilicon layer 4 is formed on the gate insulating film 6. Also, in the varactor element 14, the surface of the p-type substrate 1 is formed with an N well 2, and the gate insulating film 6 and the p-type polysilicon layer 5 are formed on the N well 2. Then, the n-type polysilicon layer 4 and the p-type polysilicon layer 5 are connected to a gate terminal 7, and the N well 2 is connected through a P+-diffuse layer 3 to an SD terminal 8. The work functions of the n-type polysilicon layer 4 and the p-type polysilicon layer 5 are made different from each other.