To reduce the decrease of a driving amplitude of a piezoelectric element when driving the piezoelectric element provided in a microscope at a high speed.

When reciprocating and driving a piezoelectric element as a linear motion mechanism at a predetermined cycle, if a drive signal is a cosine wave as shown by a curve C12, the maximum value of the driving amplitude of the piezoelectric element is decreased due to response delay of the piezoelectric element. Then, a cycle of a cosine wave component as the drive signal is shortened while a cycle of the whole drive signal is fixed, and a dormant section having a fixed value is inserted into a section where a rate of change of the cosine wave becomes zero (0) by the amount of shortening, thus obtaining a drive signal shown by a curve C13. When the piezoelectric element is driven by this drive signal, the reduction rate of the maximum value of the driving amplitude of the piezoelectric element decreasing due to high-speed driving can be reduced. This invention can be applied to a scanning type microscope.