A cylinder pressure sensor using a piezoelectric element which has high temperature resistance has been developed. The thickness shear mode in the element was utilized so as to diminish the pyroelectric effect. A ceramic pressure transfer pin inserted between the piezoelectric element and the stainless steel diaphragm is capable of shielding the heat from the diaphragm of high temperatures and also of insulating electrically the element from the housing. The characteristics of our sensor were evaluated by means of a hydraulic pressure generator and test engine. Our sensor outputs showed good matching with the reference pressure sensor outputs.