The present invention provides a stiffening element for stiffening a step-like substructure, in particular in an aircraft or spacecraft, having a foot section which is composed of a fiber composite material and is shaped in the form of a step such that it essentially fills the substructure. A method is also provided for production of a stiffening element for stiffening of a step-like substructure in an aircraft or spacecraft, according to which a profile part with a foot section which is composed of a carbon-fiber-reinforced plastic is provided, at least one layer of a glass-fiber-reinforced plastic is laminated onto the foot section, and the glass-fiber-reinforced plastic is milled corresponding to a step-like shape which essentially fills the substructure.