PURPOSE: To provide the parts arrangement position deciding device for optimumly arranging parts by deciding the positions of function blocks constituting a circuit on a printed circuit board in a parts arranging area.

CONSTITUTION: Based on connection relation, an area position decision part 103 for function block arrangement decides the positions of function blocks in the area for arrangement on the printed circuit board. A control part 105 judges whether the arranging position decision result decided by the parts arranging position decision part 104 satisfies a reference provided in advance or not. When it does not satisfy the reference, the control part 105 changes the size of the area for function block arrangement and repeatedly executes an area position decision part 103 for function block arrangement and the parts arranging position decision part 104 so as to provide optimum parts arrangement. Thus, the position of the area for function block arrangement and the arrangement of parts can be automatically decided corresponding to the characteristics of parts belonging to the function blocks and the flow of signals in the circuit.