The wiring design software 3 reads in design information, analyzes it to generate a wiring problem and correlates bonding pads and pins of a semiconductor package to each other (S102, S104). The wiring design software 3 then searches a wiring route while permitting crossing by using the Dijkstra method and the like, calculates an evaluation value by weighting the length of a candidate route with a coefficient W when the candidate route crosses a monitoring side E, and selects a candidate route having a minimum evaluation value as a partial route (S110). Finally, the result of wiring is outputted (S112)