A circuit board includes an inner circuit substrate and an outer circuit substrate electrically connected to the inner circuit substrate. The outer circuit substrate includes an outer dielectric layer and an outer circuit layer facing the inner circuit substrate embedded in the outer dielectric layer. A portion of the outer circuit layer facing away from the inner circuit substrate protruding from the outer dielectric layer. The circuit board can increase contact area between the outer circuit layer and the outer dielectric layer, improving adhesion between the outer circuit layer and the outer dielectric layer, and reducing a thickness of the outer circuit substrate, thereby reducing the overall thickness of the circuit board.