A constant velocity universal joint smoothly operates under load and during speed rotation, and also suppresses heat generation and has enhanced durability. An offset in an axial direction between a center of curvature of each of track grooves and a center of curvature of an inner surface of an outer joint member, and an offset in the axial direction between a center of curvature of each of track grooves and a center of curvature of an outer surface of an inner joint member are each set to zero. The track grooves of the outer and inner joint members are each inclined with respect to an axial line. A circumferential length of each of pockets of a cage is set so that two pockets allow balls to be assembled therein at one time under a state in which the two pockets are exposed.