A steering device for steering front wheels of a four-wheeled vehicle is disclosed, comprising a steering wheel, a steering column, a lower column, and a steering gear box. The lower column is coupled via universal joints to the steering column and the steering gear box. The steering gear box includes a housing in which a rack and a screw rod are accommodated. The rack has an end coupled via a spherical joint to a tie rod, which is jointed to the front wheel. The spherical joint includes an anti-loosening washer. The housing has an inside surface forming a step over which a sleeve is fit for being engageable with the anti-loosening washer of the spherical joint to form a constraint to an inward travel of the spherical joint of the tie rod into the housing so as to set a constraint to steering angle of the front wheel.