A weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which detects the Earth's magnetic field to obtain positional information is disclosed. The sensor comprises a first base board which is formed at its upper and lower surfaces with first driving patterns such that the upper and lower first driving patterns are electrically connected to each other, a pair of first stacked boards which are stacked on upper and lower surfaces of the first base board and which are formed with magnetic layers to be parallel to each other and patterned in a certain shape, and a pair of second stacked boards which are stacked on outer surfaces of the pair of first stacked boards and which are formed with second driving patterns electrically connected to the first driving patterns of the first base board to surround magnetic layers and formed with pickup patterns to surround the first and second driving patterns.