A circuit board structure includes a first sub-board including a plurality of circuit patterns, a second sub-board including a plurality of pads, and a connecting structure layer having a plurality of through holes and including an insulating layer, first and second adhesive layers, and a plurality of conductive blocks. The first adhesive layer is directly connected to the first sub-board. The second adhesive layer is directly connected to the second sub-board. The through holes penetrate through the first adhesive layer, the insulating layer, and the second adhesive layer. The conductive blocks are located in the through holes. An upper surface and a lower surface of each conductive block are respectively lower than a first surface of the first adhesive layer and a second surface of the second adhesive layer relatively away from the insulating layer. Each circuit pattern contacts the upper surface, and each pad contacts the lower surface.