Abstract: A safety helmet includes an outer shell juxtapositionally secured with an inner shell defining an air chamber between the two shells, a plurality of cushioning bellows retained between the two shells, an air-penetrable layer adhered on an inside surface of the inner shell disposed around a wearer's head, and a cap frame sealably combining the two shells and the air-penetrable layer to form a complete safety helmet having a great dampening effect for reducing an external impact force acting upon the helmet by the plurality of cushioning bellows between the two shells for enhancing safety of a wearer of the helmet.