A circuit board, comprising a multi-layer circuit board, a first conductive circuit, a first circuit layer, an adhesion promoter layer, a second conductive circuit, and a second circuit layer. The multi-layer circuit board comprises an inner circuit and an opening. The opening exposes the inner circuit. The first conductive circuit is disposed in the opening and on the inner circuit. The first circuit layer is disposed on the first conductive circuit in the opening and lower than the depth of the opening. The adhesion promoter layer is disposed in the opening and on the surface of the multi-layer circuit board and connected to the first conductive circuit. The second conductive circuit is disposed on the adhesion promoter layer and on the first circuit layer in the opening. The second circuit layer is disposed on the second conductive circuit in the opening and on the second conductive circuit.