This panel structure (1) is provided with a flat panel (10) and a reinforcing panel (20) at which a reference plate section (21) and a plurality of frustro-conical convexities (23) protruding from the reference plate section are formed. The flat panel (10) and the peaks (25) of the plurality of frustro-conical convexities (23) of the reinforcing panel (20) are joined by means of an adhesive (5).