PURPOSE: To make the dynamic characteristic of the apparatus smooth by correcting a driving voltage (a driving current) composed of trigonometric function waves so that a holding torque to a rotor between steps in a stepping motor is made nearly definite.

CONSTITUTION: An excitation means 3 outputs driving voltages (driving currents) composed of trigonometric function waves as voltage-(current-)corrected correction values in such a way that a holding torque to a rotor 6 between steps in a stepping motor 4 becomes nearly definite. In this case, when the driving voltages composed of the trigonometric function waves in the excitation means 3 are designated respectively as V0 sin θ and V0 cos θ (where V0 represents a peak voltage value and 9 represents a driving electric angle), the correction voltages V sin, V cos in the excitation means 13 are output as correction values including an f function so as to be V sin = V0 [1+f (sin 2θ)] sin θ and V cos = V0 [1+f (cos 2θ)] cos θ. Thereby, the characteristic of a mechanical rotating operation with reference to a change in the driving electric angle of the stepping motor becomes smooth.