A circuit board includes a circuit layer, a first solder resist layer, a second solder resist layer and at least one conductive bump. The first solder resist layer is disposed on a lower surface of the circuit layer and has at least one first opening exposing a portion of the lower surface of the circuit layer. The second solder resist layer is disposed on an upper surface of the circuit layer and has at least one second opening exposing a portion of the upper surface of the circuit layer. The conductive bump is disposed inside the second opening of the second solder resist layer and directly connects to the upper surface of the circuit layer exposed by the second opening. A top surface of the conductive bump is higher than a second surface of the second solder resist layer.