A method for determining a wiring pattern of a signal line for connection of a circuit on a multi-layer printed wiring board includes the steps of providing a constraint of an electrical length which the signal line must satisfy, determining an electrical length change at a discontinuous delay part of the signal line along which a signal propagates, determining a wiring route of the signal line, calculating an electrical length of the signal line with use of a wiring length of the signal line and the determined electrical length change, judging whether or not the calculated electrical length satisfies the electrical length constraint given to the signal line, and determining the wiring route as a wiring pattern when the electrical length constraint is satisfied as the decision result, thereby carrying out a wiring layout to make an electrical length constraint satisfied.