PURPOSE: To display a cross-sectional view at a designated part accurately through optimal operation by preparing measurement data at each coordinates on a line connecting between two designated points on a gray image in the form of one-dimensional array and then rotating the measurement data.

CONSTITUTION: When image processing is carried out at a data processing section 13, measurement data is fit onto a plane by the method of least squares. Inclination correction is then performed such that an average plane will be in parallel with XY plane and the corrected data is substituted for a new two-dimensional array B. The two-dimensional array B is employed in the formation of a gray image which is described on a monitor section 14. Two points for determining a profile required for formation of a cross-sectional image are then designated on the gray image thus displayed. Measurement data between the two points is read out from a two-dimensional array A. The measurement data is substituted for a one-dimensional array C. Inclination of the array C is then rotary corrected through coordinates conversion such that a profile defined by two points will become horizontal. Corrected array C is then emphasized and employed in describing a profile on the monitor section 14.