PURPOSE: To simplify the input of three-dimensional form data to improve the efficiency for data input by setting the same attribute to sides on two-dimensional plans indicating the same edge line of a registered article to relate respective two-dimensional plans to one another.

CONSTITUTION: A two-dimensional trihedral figure 3 of the registered article is modeled to respective two-dimensional plans, and the same attribute is set to sides on two-dimensional plans indicating the same edge line to relate two-dimensional plans to one another. A point data file 3a consisting of XYZ coordinate values of constituting points of the article and sequential numbers corresponding to these XYZ coordinate values is generated. Sequential numbers are displayed n corresponding positions on a two-dimensional plan 1a by a two-dimensional CAD device, and contents of the point data file 3a are checked based on display contents. Thus, the input of three-dimensional form data for flux analysis is simplified to improve the efficiency for data input.