PURPOSE: To improve the strength of a rack tooth and to enlarge the steering gear ratio, by employing a special form of a pinion gear and working the rack tooth while performing the relative motion corresponding to the predetermined variable gear ratio.

CONSTITUTION: In the proximity of the neutral position of a pinion 4 where the gear ratio is at the lowest, the pressure angle β between the tooth faces 14a, 15a of the pinion 4 gearing with the rack 7 is made smallest smaller than the pressure angle of other tooth face, and while maintaining the pressure angle relating to other teeth 12, 13, 16 to the referential level the pinion tooth profile is formed. The rack 7 is worked by said pinion tooth profile while performing the relative motion corresponding to the predetermined variable gear ratio between the rack and the pinion to form the tooth profile of the rack 7.