PROBLEM TO BE SOLVED: To make detectable both vibration and acoustic emission simultaneously by encasing cables for taking out the output from a sensor body section comprising a damper material bonded to a piezoelectric element and an electrode plate and taking out the output from one ends on the piezoelectric element side and the damper side. SOLUTION: A composite sensor is inserted into a case 7 and the plus (+) pole side of two piezoelectric elements is fixed while sandwiching an electrode plate (+) 3 while a damper member 2 and an electrode plate (-) 4 are fixed sequentially on the (-) pole side on the upper piezoelectric element face. A plus side lead wire 10 is connected with the core side terminal of a connector 8 and a minus side lead wire 12 is grounded to a case 7 made of a metallic material on the earth side of a connector 8. A piezoelectric element fixing base 5 is insulated from the case 7 and a piezoelectric element 1 having hollow central part is fitted over a central protrusion 12. At the end part of the protrusion 12, the sensor body section comprising the piezoelectric element 1, the damper member 2 and electrode plates 3, 4 is tightened by means of a screw.
