A manufacturing method of a circuit board comprises the following steps. Firstly, provide a first core layer, a second core material layer, and a central dielectric material layer. Secondly, press the first core layer, the second core material layer, and the central dielectric material layer to form a composite circuit structure. Thirdly, removing a portion of the central dielectric material layer located at a periphery of a pre-removing area and a portion of the second core material layer located at the periphery of the pre-removing area. Finally, remove a portion of the central dielectric material layer located within the pre-removing area and a portion of the second core material layer located within the pre-removing area to form a central dielectric layer and a second core layer.