To surely detect ampere-hours of an alternating current of high frequency.

A silicon substrate 2 is joined onto a surface of a glass substrate 1. A plane movable part 13 is provided in a support part 11 of the silicon substrate 2 via four flexible parts 12A, 12B, 12C, 12D. A first conductor wiring 14 extended linearly is provided in the movable part 13, a second conductor wiring 15 extended in substantial parallel to the wiring 14 in a support side edge part 11C of the support part 11, and a piezoelectric resistance element 16 is attached to the flexible part 12D. The movable part 13 is displaced thereby horizontally by Lorentz's force when currents flow in the first and second wirings 14, 15, and the piezoelectric resistance element 16 detects ampere-hours conducted in the first and the second wiring 14, 15.