To provide a voltage-controlled variable capacitative element which can be manufactured without changing existing manufacturing process or adding any new process, and does not enlarge the circuit size nor require higher voltage, and in which the C-V characteristic is arbitrarily chosen.

Varactor elements 13 and 14 are formed on the surface of a p-type substrate 1. The varactor element 13 is formed by forming an N-well 2 on the surface of the P-type substrate 1, forming a gate insulating film 4 thereon, and forming a polysilicon layer 9 thereon. The varactor element 14 is formed by forming an N-well 2 on the surface of the P-type substrate 1, forming thereon a gate insulating film 5 which is thicker than the gate insulating film 4, and forming a polysilicon layer 9 on the gate insulating film 5. Furthermore, the polysilicon layers 9 are connected to a gate terminal 7, and the N-wells 2 are connected to a SD terminal 8 via P+ diffusion layers 3.