A creasing machine includes a creasing tool, a counter element cooperating with the creasing tool, and a transportation system for advancing sheets through a creasing area between the creasing tool and the counter element, wherein the creasing tool has a creasing plate provided with at least one creasing projection, and wherein the creasing projection on the creasing plate is constituted by a plurality of small, plastically deformed areas which merge into each other so as to form the creasing projection.