PURPOSE: To efficiently carry piping design work conforming to a design rule by judging automatically the verification of the design rule, and displaying a part violating the design rule for an operator.

CONSTITUTION: A means 1 to display the five-side drawing or the three-side drawing of a manifold block on a CRT display screen 6, a parts arranging means 2 to arrange plural hydraulic parts obtained from the drawing of a hydraulic circuit on the five-side or the three-side drawing on the basis of the operation of the operator, and an automatic piping means 3 to pipe and connect between plural hydraulic parts by shortest path search processing when connection points between plural hydraulic parts are designated are provided. In this case, after the hydraulic parts are arranged by the parts arranging means 2, or after piping connection between plural oil hydraulic part is completed by the automatic piping means 3, or when the operator verifies whether the manifold block satisfies the design rule or not as occasion demands, a place not satisfying the predetermined design rule is judged and displayed by providing a design rule verifying means 7.