PURPOSE: To attain automatic arrangement densely without need for a troublesome operation by designating a shape stored in a memory in the CAD system and a straight line element being a partial component of the shape to the CAD system.

CONSTITUTION: A CPU 1 starting 'shape arrangement processing' in response to a menu selection operation by the operator at a tablet device 9 displays a guidance message representing the selection of straight lines for the arrangement reference onto a graphic display screen of a CRT 4 at first and enters the standby state awaiting the selection of the straight line by the operator by a pickup operation using a graphic cursor. When the operator executes the pickup operation and selects the straight line used for the arrangement, the CPU 1 detects it by discrimination processing and reads the data relating to the picked up straight line from a shape data storage memory being a RAM 3 and stores the data in a work memory of the RAM 3.