The constant velocity universal joint includes a plurality of vehicle body attachment flanges provided apart from each other in the outer circumferential direction of the joint outer ring and partly protruding in the radial direction. The joint outer ring has a flower outer circumferential shape corresponding to the inner circumferential shape, and the vehicle body attachment flanges are provided at outer recesses positioned between the track grooves of the joint outer ring. In this joint, the number of the balls is six, and the pitches of the ball tracks are random, unequal and not less than 55 degree.