Abstract: Route nets having at least one current path through which a current flows are extracted from among a plurality of route nets each representing a line that interconnects elements of an electronic circuit in electrical connecting relationship from information on an electronic schematic. The extracted route nets is separated into a first subnet of lines where currents flow and a second subnet of lines where no currents flow. A route is determined for each of the first and second subnets. Points on the routes for the first and second subnets are interconnected by another route.