To provide a variable capacitor which has a large electrostatic capacity change to an applied voltage, and a high Q value.

A first electrode layer 2 and a second electrode layer 3 are both formed of conductive material and provided confronting each other. A first dielectric layer 4 formed of electrostrictive material is interposed between the first electrode layer 2 and second electrode layer 3. A tensile force perpendicular to the direction A of lamination is given to the first dielectric layer 4 by a tensile force applying means 5. The tensile force applying means 5 comprises a third electrode layer 6 and a fourth electrode layer 7, which are formed of conductive material and disposed confronting each other, and a second dielectric layer 8, which is formed of piezoelectric material and interposed between the third electrode layer 6 and fourth electrode layer 7. The third electrode layer 6 is laminated on the first electrode layer 2.