Abstract: A multi-layered electrostrictive effect element comprises films or thin plates of an electrostrictive material and inner electrodes alternatively arranged in layers, the inner electrodes being formed on the entire surface of the films or thin plates of the electrostrictive material, wherein the insulating layer which insulates the inner electrodes exposed on the side end faces of the element comprises a polyimide resin having repeating units represented by the following general formula (I): ##STR1## (wherein X represents a tetravalent group selected from the group consisting of tetravalent phenyl groups; tetravalent biphenyl groups; and tetravalent polyphenyl groups in which at least one of either the phenyl or bipheny groups are bonded through at least one member selected from the group consisting of O, CO, S, CH.sub.2, C(CH.sub.3).sub.2 and C(CF.sub.3).sub.

Abstract: The present invention relates to a longitudinally effective piezoelectric element exhibiting a large displacement at low voltage and to a ceramic composition suitable for producing the longitudinally effective piezoelectric element.