To provide a variable capacitance capacitor with high Q value which has large capacitance variation caused by applied voltage.

The variable capacitance capacitor comprises a dielectric substance composed of an electrostrictive material, and a first electrode and a second electrode which sandwich the dielectric substance so as to form an electrostatic capacity region. The dielectric substance comprises a third electrode and a fourth electrode which sandwich the vicinity of the electrostatic capacity region so as to form an electrostriction generating region, and can characteristically adjust an electrostatic capacity value between the first electrode and the second electrode by applying electric field between the third electrode and the fourth electrode.