To lower the cost while reducing the man-hours by forming an irregular surface corresponding to a rack teeth in the inner peripheral surface of a tubular body provided in a back surface of the rack teeth formed in the peripheral surface of the tubular body in the axial direction.

An arc part 8 of a U-shaped body 10 is formed with rack teeth 11. A work of the U-shaped body 10 is fitted on an inner block 16 so that the arc part 8 is positioned upper like an inverted U-shape, and an outer block 15 is arranged outside of a side wall 9 and inside of a restraining block freely to be moved upward and downward. The outer block 15 is formed with a rack teeth mold 18, and an irregular surface 19, having a nearly waved cross section corresponding to the rack teeth mold 18 is flattened in an upper part of the inner block 16. With this structure, a tubular light steering rack shaft can be manufactured at a low cost without having a work wall thickening process.