Patent ID: 7591205

Claim:
A ball screw comprising: a screw shaft having a screw groove in a spiral shape at an outer peripheral face thereof; a nut having a screw groove opposed to the screw groove of the screw shaft at an inner peripheral face thereof; a plurality of balls rotatably disposed in a ball rolling path in a spiral shape that is defined by the screw grooves of the screw shaft and the nut, wherein the nut is provided with a ball return path for circulating the balls by delivering the balls from an end point to a start point of the ball rolling path; a ball guide member fit to a recess portion provided at an end face of the nut for guiding the balls between the ball rolling path and the ball return path; and a fixing member for fixing the ball guide member to the nut, wherein a portion of the fixing member is inserted to a groove portion formed at an inner face of the recess portion in such a manner that the ball guide member is pressed by the fixing member against the nut, and wherein the groove portion extends along only a part of a circumferential direction about a central axis of the nut.