A method and an apparatus for automatically shaping traces by using computation comprises: setting means that sets an equiangular octagon circumscribing a clearance circle indicating a position where clearance can be secured from vias so that one side of such equiangular octagon is in parallel with a reference line; setting means that sets, with respect to the existing trace having a segment passing between the vias, an equiangular octagon circumscribing a circle that is centered on a center position of the via in the closest vicinity of such segment and that is tangent to such segment so that one side of such equiangular octagon is in parallel with the reference line; correction means that corrects the existing trace in the vicinity of the via so that the trace overlaps any side of the equiangular octagon set with respect to such via; and correction means that connects two segments obtained by the correction means by a segment in a direction of "45.times.n" degrees with respect to the reference line.