In a method of manufacturing a hollow rack shaft, an approximately rectangular plate having a wide rack tooth portion, is bent lengthwise into a gutter-like cross section to provide: at the central portion, a flat bottom portion on which rack teeth are formed later and a pair of mutually facing leg portions, and, in the vicinity of both ends, a semicircular bottom portion and a pair of mutually facing leg portions. The mutually facing leg portions at the central portion have a larger clearance than the clearance of the mutually facing leg portions in the vicinity of both ends. The rack teeth are then formed on the flat bottom portion through the plastic flow of the flat bottom portion and a part of material of the pair of leg portions of this flat bottom portion. The gutter-shaped plate, on which the rack teeth have been formed, is then formed into a tube having a hollow inner surface, by bending the plate and butt joining the edge portions.