The study deals with X-ray CT technology to inspect the inside parts of workpiece without destroying them. At present, there is few softwares capable of processing X-ray CT scanned data. Therefore, the function was developed to treat the data to evaluate geometric elements such as straight lines, circular arc and others, based on 3-dimensional CAD data as the standard of inspection. After the coordinate system of scanned data is automatically related with the 3-dimensional CAD data, the system evaluates geometric elements considering that a workpiece contour consists of a cluster of segments. Thus, the system cuts the contour of 3-dimensional CAD data on the appointed cross-sectional planes and classifies them into geometric elements. To compare 3-dimensional CAD data with the X-ray CT scanned data, the system calculates the straightness, angle deviation from the direction vector, length and its error of a straight line, and, roundness, deviation of center point, radius and its elTor. In addition, the system offers a visualization interface to display them so that the users utilize the evaluated result comfortably. As a result, the system is found effective to evaluate 2-dimensional geometric elements.