As a stopper for restricting movement of a rotary shaft 31 of a transmission device 3 and a shaft part 41 of a first drive-side joint member J11 in a direction of approaching each other, a stopper part 5 is formed separately from the shaft part 41 and a yoke body part 42 of the first drive-side joint member so that the stopper function of the first drive-side joint member J11 is guaranteed by the separately-formed stopper part 5 in the present invention. With this configuration, a change in the gravity center position of the first drive-side joint member caused due to build-up processing on the shaft part or the yoke body part is suppressed. It is possible to restrict relative movement of the first drive-side joint member and the rotary shaft while ensuring adequate machining for formation of a shaft-part-side seal surface on the first drive-side joint member.