PURPOSE: To clearly reflect the purpose of a designer on a three-dimensional shape with a simple operation by displaying and confirming the instruction shown on the two-dimensional projection chart and the instruction shown on the three-dimensional shape with relation secured between both instructions in regard of a three-dimensional element designating method.

CONSTITUTION: A projection chart processing part 6 produces a two-dimensional projection chart and selects a three-dimensional, element in response to the designated element out of the projection chart. A three-dimensional shape display processing part 7 shows a three-dimensional shape. Then the projection chart produced by the part 6 is displayed and the corresponding element of the three- dimensional shape is selected for the element designated by a user. This selected element is displayed with emphasis on the three-dimensional form displayed by the part 7. If a single element is displayed with emphasis, this element is defined as a three-dimensional shape element. Meanwhile the element designated by the user is decided as a three-dimensional shape element if plural elements are displayed with emphasis.