An electrically driven power steering apparatus is structured such that a
large impact on a rack shaft occurs upon an impingement of a steering
stopper, and, even when an axial force acting on a ball bearing of a
presser member becomes zero, a rotation of the presser member is hindered
by caulking c at a thin plate member. Therefore, the presser member does
not slacken, and a predetermined axial force can be given again to the
ball bearing when the impact dissipates. The thus structured power
steering apparatus exhibiting, though the cost is low, an excellent
shockproof characteristic and capable of preventing the bearing from
coming off a ball screw nut, can be provided.