A circuit board structure includes a circuit substrate having opposing first and second sides, a redistribution structure disposed at the first side, and a dielectric structure disposed at the second side. The circuit substrate includes a first circuit layer disposed at the first side and a second circuit layer disposed at the second side. The redistribution structure is electrically coupled to the circuit substrate and includes a first leveling dielectric layer covering the first circuit layer, a first thin-film dielectric layer disposed on the first leveling dielectric layer and having a material different from the first leveling dielectric layer, and a first redistributive layer disposed on the first thin-film dielectric layer and penetrating through the first thin-film dielectric layer and the first leveling dielectric layer to be in contact with the first circuit layer. The dielectric structure includes a second leveling dielectric layer disposed below the second circuit layer.