A stepping motor driving device includes a table, a driving pulse control part, an interpolation number indicating part and a driving part. The table stores thinned data which is thinned from original data and designates a pulse width of a driving pulse relating to a slow-up control or a slow-down control of a stepping motor. The driving pulse control part sequentially reads the thinned data from the table at predetermined intervals, to interpolate the thinned data in accordance with a given interpolation number so as to generate interpolated data and to output the driving pulse with the pulse width designated by the thinned data or the interpolated data by sequentially using the thinned data and the interpolated date at predetermined intervals. The interpolation number indicating part indicates the interpolation number to the driving pulse control part. The driving part drives the stepping motor in accordance with the driving pulse.