A circuit board having an interior space includes a multi-layer structure and a compartmentalized frame embedded in the multi-layer structure. The multi-layer structure has a plurality of plates stacked along a stacking direction and a gel combining any two adjacent plates. The plates include two outer plates and at least one inner plate arranged between the outer plates. The compartmentalized frame defines a predetermined space. The compartmentalized frame is arranged between the outer plates and substantially abuts the outer plates. The compartmentalized frame is arranged in a path of a flowing direction of gel which flows toward the predetermined space to prevent any gel from flowing into the predetermined space. Thus, the circuit board of the instant disclosure is provided with the interior space accurately formed by embedding the compartmentalized frame.