A manufacturing method of a circuit board is disclosed. The manufacturing method of a circuit board in accordance with the present invention includes forming a separation layer on a carrier, stacking an adhesion layer which is coupled to the carrier and covers the separation layer, forming a circuit layer on the adhesion layer, forming a circuit board unit by cutting the separation layer, the adhesion layer and the circuit layer such that the separation layer is separated from the carrier, and forming a stiffener by processing the separation layer of the circuit board unit. The manufacturing method of a circuit board in accordance with the present invention can reduce the cost and time for forming the stiffener by forming the stiffener together in the manufacturing process of the circuit board.