Abstract: The invention relates to a piezoelectric acceleration sensor and to a piezoelectric acceleration device which use a film piezoelectric element.Speicfically, the piezoelectric acceleration sensor and the piezoelectric acceleration sensor device generate relatively large outputs when acceleration occurs along the sensing axis, but produce relatively small outputs from acceleration perpendicular to the sensing axis. In addition, the sensor and the sensor device are relatively unaffected by temperature fluctuations and are highly impact-resistant.

Abstract: A piezo-electric acceleration sensor, including: a piezo-electric polymer membrane element having an element through-hole; a diaphragm having a diaphragm through-hole and attached to the piezo-electric membrane element so that the diaphragm hole is concentric to the element through-hole to form a laminate with a laminate through-hole; and a fixing mechanism, having a sensing hole, for fixing the laminate in a stretched manner, and wherein: the laminate through-hole has about 2.25 to about 80% of the area of the sensing hole; and the diaphragm and the piezo-electric element meet the equation:(Eb.times.Tb.sup.3)/(Ep.times.Tp.sub.3).gtoreq.about 5wherein Eb, Tb, Ep and Tp are Young's modulus thickness of the diaphragm, Young's modulus, and thickness of the piezo-electric element, respectively, whereby acceleration, applied to the diaphragm, is detected based on a quantity of electricity generated due to strains in a piezo-electric element.