First, initial routing is performed on a net. If a design rule error exists in a wire already routed as a result of the initial routing, the wire already routed, causing the design rule error, is removed. Next, if the wire already routed and removed is a wire interconnecting a movable terminal, freely placeable within a predetermined region, to another terminal, then the movable terminal is displaced within the predetermined region and the removed wire is re-routed such that the displaced movable terminal is interconnected to the other terminal. Accordingly, the movable terminal can be located at an appropriate position within the predetermined region in accordance with the situation of surrounding wires. As a result, routing results of a higher density can be obtained.