A manufacturing method of a magnetic element includes the following steps: forming a block including a central post and at least one lateral post with magneto-conductive materials; cutting the block along a first plane passing through the central and lateral posts to form a first half body and a second half body; combining the first half body with the second half body to form a first air gap between the central post of the first half body and the central post of the second half body and a second air gap between the lateral post of the first half body and the lateral post of the second half body; and cutting or grinding the combined first half body and second half body along a second plane passing through the central post and the lateral post to form a third half body including the first and second air gaps.