PURPOSE: To measure weight and width of a passing body accurately by providing a piezoelectric sensor made of piezoelectric bodies divided into the plural in the direction of the way width on a passing way of the body and obtaining a signal in proportion to the pressure from between electrodes of the piezoelectric bodies.

CONSTITUTION: The piezoelectric sensor 5 is constituted of the piezoelectric bodies 6aW6f divided into six in the direction of the way width and a shared electrode 9 having the electrodes 8aW8f and the protrusions 9aW9f provided between the respective piezoelectric bodies 6aW6f and a base, and the signal in proportion to the pressure is obtained. Then, the piezoelectric sensor 5 is provided on the passing way W of the body and connected with a signal processor 11 via multiplexers 10a and 10b. When the body G moves on the passing way W and presses the protrusions 9aW9f of the piezoelectric sensor 5, the signal in proportion to the pressure is obtained from between the electrodes 8aW8f and processed with the signal processor 11 and the weight and width of the body G are measured accurately.