To precisely set a product at the time of a leak test and to prolong the life of an O ring.

This device is equipped with 1st and 2nd cylindrical members 15 and 17, an O ring 26, a cylindrical slide member 5, and a supply means. The 1st and 2nd cylindrical members 15 and 17 are formed cylindrically and the hub 50a of a torque converter 50 is inserted. The O ring 26 is arranged in an annular groove 25 formed of both the cylindrical members 15 and 17, and the O ring is able to abut against the outer peripheral surface of the hub 50a and exposed on the outer peripheries of the cylindrical members 15 and 17. The slide member 5 is arranged at the outer periphery of the 1st cylindrical member 15 movably along the axis and can be at a standby position where it is separated from the O ring 26 and a seal position where the O ring 26 is pressed against the outer peripheral surface of the hub 50a inserted into both the cylindrical members 15 and 17. The supply means supplies gas or liquid into a torque converter.