A piezoelectric vibrator 2 that generates an electric charge according to a stress and a weight 1 provided on the piezoelectric vibrator 2 are included. The piezoelectric vibrator 2 has multiple pairs of sensing electrodes 3a and 3b, and 4a and 4b, and the sensing electrodes 3a and 3b, and 4a and 4b are respectively connected in parallel so that capacitances Cd1 and Cd2 made of the sensing electrodes may be connected in parallel. It is thus possible to double the charge sensitivity with keeping the voltage sensitivity.