As shown in FIG. 11, four of the vias 225, which are located outward in the front-rear direction, are formed at positions which overlap with the positioning members 143, respectively. Each of these vias 225 removes the positioning member 143 corresponding thereto at least in part, and thereby adjacent two of the magnetic pieces 141 are divided from each another. In other words, the method of manufacturing the circuit board 20 according to the present embodiment is provided with forming the vias 225 which pierce the first substrate member 12 and the second substrate member 16 so as to pass through the cavity 121, and thereby the positioning members 143 are removed at least in part so that the magnetic pieces 141 are divided from one another.

As understood from FIG. 12, a diameter size of the via 225 is equal to or larger than a size of the positioning member 143 in the front-rear direction. In other words, the forming of the via 225 is carried out so that the diameter size of the via 225 is larger than a width size of the positioning member 143 in a width direction (the front-rear direction) perpendicular to the predetermined direction. This is because when the diameter size of the via 225 is smaller than the width size of the positioning member 143 in the front-rear direction, the magnetic pieces 141 adjacent to each other remain coupled with each another. In other words, this is because the magnetic pieces 141 adjacent to each other are not divided from each other by forming of the vias 225 and the desired magnetic characteristics for the circuit board 20 are not obtained.