An instrument with multi-probe method was developed for the cylindrical-figure measurement. When scanning motion with single displacement probe is made in measuring a cylindrical-figure, the spindle and carriage with very high accuracy is needed as the mechanical datum. Regarding the fatal difficulty of preparing a set of spindle and carriage with adequate accuracy, particularly for heavy and large sized work pieces, a software datum method with multi-probe output was employed to separate motion errors from probe output. Following the analysis of the influence of error motions on the probe output, the inverse Filtering Method, one of the methods of software datum, was applied. Based on the result, we developed a measuring instrument. Experiments using this instrument confirmed the effectiveness of the method.