To provide a cylinder manufacturing apparatus with which a non-flat cylinder is easily manufactured from a plate, and a non-flat cylinder of different diameter is formed with the use of a single mandrel resulting in enhancement in the manufacturing efficiency and reduction in the manufacturing cost.

The cylinder manufacturing apparatus comprises: a mandrel around which a fed plate-like work is wound to be formed into a cylindrical shape; a welding means to weld a rear end of the work wound around the mandrel to an outer surface of the work; and a pushing apparatus to deliver the work from the mandrel, wherein the mandrel 18 is composed of at least three split bodies arranged radially around the winding axis O, and at least three split bodies 18A-18F are moved radially to constitute the mandrel 18 into a substantially columnar body of an optional outside diameter.