PURPOSE: To prevent the shift of a gasket in a retainer which is constituted so that a circular annular gasket interposed between the edge surfaces of a pair of tubular coupling members is held on one coupling member. CONSTITUTION: A retainer 5 consists of a circular annular part 25, gasket holding part 26 which is installed in projection inward the circular annular part 25 and is equipped with a plurality of hooks 28 holding the outer peripheral surface of a gasket 3, and a coupling member holding part 29 which is installed on the circular annular part 25 and is engaged with the edge surface of one coupling member 1. COPYRIGHT: (C)1993,JPO&Japio