A circuit board including a first dielectric layer having a first surface and a second surface, a first circuit layer, a second dielectric layer, and a second circuit layer is provided. At least one trench is formed on the first surface, and the first circuit layer is formed on an inside wall of the trench. In addition, the second dielectric layer is disposed in the trench, and covers the first circuit layer. The second circuit layer is disposed in the trench, and the second dielectric layer is located between the first circuit layer and the second circuit layer. A manufacturing method of the circuit board is further provided.