Abstract: A routing method for wiring design including a determining step for identifying, in one of the wiring sections where no wiring path is determined as yet, the direction of the line segment which is prohibited by an obstacle and accordingly determining a wiring path. The routing method also includes a generating step for generating, on a layer opposite to the layer on which one unprocessed line segment is present and in a position having the same plane coordinates as the line segment, an obstacle which prohibits only such line segments as are parallel in direction to the line segment, on the wiring path determined by the determining step.