Disclosed is a printed circuit board with a weak magnetic field sensor according to the present invention, which includes a substrate having first excitation circuits and first detection circuits formed on both sides thereof. First laminates are layered on both sides of the substrate, and have soft magnetic cores with a predetermined shape formed thereon. Second laminates are layered on the first laminates, and have second excitation circuits and second detection circuits, connected through via holes to the first excitation circuits and first detection circuits, respectively, so that the first and second excitation circuits and first and second detection circuits are wound around the soft magnetic cores, formed thereon. The soft magnetic cores each include a magnetic core and non-magnetic metal layers formed on both sides of the magnetic core.