To cancel a magnetic field in an interconnection pattern of a printed wiring board.A first interconnection pattern 3a is formed on a surface 1a of an insulating substrate 1. A second interconnection pattern 5a is formed on a bottom surface 1b of the insulating substrate 1 so as to be superposed on a meandering part of the first interconnection pattern 3a when viewed from the upper surface side. An end part 5b of the second interconnection pattern 5a is electrically connected to an end part 3d of the first interconnection pattern 3a via through holes 7a. The first interconnection pattern 3a and the second interconnection pattern 5a form a single interconnection line via the through holes 7a. Accordingly, the first interconnection pattern 3a and the second interconnection pattern 5a are 180.degree. different from each other in the direction in which current flows.