To improve sealing performance and maintenance workability of a constant velocity universal joint used under an inferior environment.

The constant velocity universal joint includes: an outer joint member 11 provided on a first shaft member 2; an inner joint member 12 provided on a second shaft member 3; a ball 14 as a torque transmission member arranged between both joint members 11, 12; and a sealing device 30 for sealing an opening part 15 between both the joint members 11, 12. One end 21 is fixed on a cover mounted flange 4 provided on the second shaft member 3 to be extended in an axial direction, and a cylindrical cover material 20 forming a radial gap 40 extended in an axial direction between the outer joint member 11 stored in the inner circumference and the sealing device 30 is provided. A ring-like projection part (A) partly reducing a gap width of the radial gap 40 is provided on at least one of two opposed faces forming the radial gap 40. Herein, the ring-like projection part (A) includes a ring-like projection 23 formed on an inner diameter face of the cover material 20.