To increase suction quantity of an impact stroke by arranging a movement allowing mechanism for allowing a relative slide movement of a constitutive part of a constant velocity joint when shaft directional force acts on a propeller shaft, and forming a shaft inserting space in a part held by a center support of a joint flange.

A propeller shaft 2 for connecting the transmission side and the differential side of a vehicle is composed of a propeller shaft 2-1 connected to the differential side by a front side joint 4 of a vehicle and a propeller shaft 2-2 connected to the transmission side by a rear side joint 6 of the vehicle. Both propeller shafts 2-1, 2-2 are connected by a double offset type joint 8 being a sliding constant velocity joint, a joint flange 10 forming a hollow space S and a connecting flange mechanism 12. In this joint 8, when shaft directional force acts on the propeller shaft 2, a relative slide movement of a constitutive part such as an inner ring 14 is allowed to the propeller shaft 2 by a movement allowing mechanism 22.