To reduce the number of processings and to enhance shape accuracy by forming a displacement enlarging portion and a driving portion on the same axis and differentiating both spring constants.

The present chopper device comprises a tongue shaped displacement enlarging portion 14 in which a slit 15 is provided on a portion of a flat spring 12 and which has a curved portion 16 at a tip end of the flat spring 12; and a driving portion 17 to which a piezoelectric substance 13 is adhered to a fixed end 11 side of the flat spring 12. A center axis a of the displacement enlarging portion 14 and the driving portion 17 is the same. Here, when an electric field of a constant frequency is charged to the piezoelectric substance 13, a flexural oscillation is generated by a piezoelectric effect, the flexural oscillation is also excited in the displacement enlarging portion 14 and the curved portion 16 of a free end periodically vibrates. At this time, the curved portion 16 is stabilized and a big displacing action is obtained by differentiating and appropriately setting a resonance frequency of the driving portion 17 and the displacement enlarging portion 14. Since a bent processing is carried out only in the curved portion 16, the number of processings is reduced to 1/3 of the conventional processings and since a dispersion factor exists at only one position, shape accuracy is also enhanced.