In the circuit board of Patent Document 1, the cavity corresponds to the magnetic member in a one-to-one relationship. In order to form a magnetic core provided with dispersed gaps by the use of this structure, a plurality of cavities and a plurality of magnetic pieces corresponding to the cavities, respectively, are necessary. Here, there is a space between each of the cavities and the magnetic piece corresponding thereto in general. Accordingly, positions of the magnetic pieces each of which is place in the cavity corresponding thereto may have variations, and a gap between adjacent two of the magnetic pieces may have variation. As a result, the magnetic core formed by the use of the structure of Patent Document 1 and provided with the dispersed gaps has a problem that desired characteristics may not be obtained.

It is therefore an object of the present invention to provide a method of manufacturing a circuit board, wherein the method can arrange a plurality of magnetic pieces at regular intervals in a cavity formed in a substrate. Moreover, it is another object of the present invention to provide a circuit board having a plurality of magnetic pieces placed in a cavity thereof and arranged at regular intervals.