The present disclosure provides a symmetric double offset constant velocity joint comprising: an outer race having an outer race track formed on its inner surface; an inner race having an inner race track formed on its outer surface; balls disposed between the outer race and the inner race; and a cage disposed between the outer race and the inner race for supporting the balls, wherein the outer race track includes an outer race linear track, an outer race outer curved track formed outside the outer race linear track, and an outer race inner curved track formed inside the outer race linear track, wherein the inner race track includes an inner race linear track, an inner race outer curved track formed outside the inner race linear track, and an inner race inner curved track formed inside the inner race linear track, wherein the center point of the outer race outer curved track, the center point of the outer race inner curved track, the center point of the inner race outer curved track, and the center point of the inner race inner curved track are arranged on an offset eccentric axis line spaced apart from the central axis of the outer race by a first distance in a vertical direction.

A constant-velocity universal joint includes: an outer ring; an inner ring; a plurality of balls that engages with the outer-ring ball grooves and the inner-ring ball, grooves; and a holder that is interposed between an inner spherical surface of the outer ring and an outer spherical surface of the inner ring and in which a holding window for holding the plurality of balls is formed. A chamfered portion is formed in the inner ring. The chamfered portion includes a linear section portion that is formed in a linear shape in a section perpendicular to a moving locus of the center of the corresponding ball and an arc section portion that is formed in a protruding arc shape in the section perpendicular to the moving locus of the center of the corresponding ball.

A constant-velocity universal joint includes: an outer ring; an inner ring; a plurality of balls that engages with the outer-ring ball grooves and the inner-ring ball, grooves; and a holder that is interposed between an inner spherical surface of the outer ring and an outer spherical surface of the inner ring and in which a holding window for holding the plurality of balls is formed. A chamfered portion is formed in the inner ring. The chamfered portion includes a linear section portion that is formed in a linear shape in a section perpendicular to a moving locus of the center of the corresponding ball and an arc section portion that is formed in a protruding arc shape in the section perpendicular to the moving locus of the center of the corresponding ball.