A circuit board including a substrate, a patterned circuit layer and a photo-imaginable dielectric layer is provided. The substrate has a first surface and a second surface opposite to each other. The patterned circuit layer is disposed on the first surface, and a line width of the patterned circuit layer gradually reduces from the first surface towards the second surface. The photo-imaginable dielectric layer is disposed in the substrate corresponding to the patterned circuit layer. In addition, a manufacturing method of the circuit board is also proposed.