PURPOSE: To obtain parts arrangement capable of effectively executing auto matic wiring in respect to the automatic parts arrangement system for circuit parts on a printed board.

CONSTITUTION: This automatic parts arrangement system is provided with a parts area expanding part 10 for expanding a parts area allocated to parts on the printed board and a parts arranging part 11 for finding out the proper arrangement of parts based upon the part area of respective parts allocated by the expanding part 10. The expanding part 10 calculates an arranged part area obtained by adding a wiring area required at the time of arranging parts on the board to the original part area inherent in each part and calculates an adle area on the board based upon a difference between the arrangement enabled area of the board and the sum of arrangement parts area of respective parts. The expanded parts area is calculated by expanding the arranged parts area in accordance with the size of the idle area and the parts arranging part 11 finds out the proper arrangement of parts based upon the parts area of respective parts calculated by the expanding part 10.