Provided is a method of manufacturing a circuit which includes: (a) providing a substrate made of a conductive material; (b) etching a first surface of the substrate excluding a region in which at least one via is to be formed; (c) etching a region of the etched first surface of the substrate in which an insulated portion of a first circuit is to be formed; (d) stacking a first insulation layer in spaces formed by the etching performed in operations (b) and (c); and (e) grinding a second surface of the substrate to expose the first insulation layer outward along with the first circuit, thereby forming a circuit board.