PURPOSE: To reduce the labor required for connection of flexible tube to a fitting which includes a fitting main body fastening member and a pair of retainers whereby pushing the flexible tube for connection, by holding a pair of the retainers and providing a retainer holding body and a resilient member.

CONSTITUTION: A fitting A includes a fitting main body 1, cap nut (fastening member) 2, a pair of retainers 3, 4, a retainer holding body 5 and a spring 6. A fitting main body 1 is formed with a connecting hole 13, and the cap nut 2 is formed with a through-hole 20 at the central portion thereof. The through- hole 20 is constituted of a guide hole 21 having a diameter larger than that of a flexible tube P. Each of the retainers 3 and 4 is formed in a half-cylinder shape and is formed in a bellows-shape on its inter peripheral surface. The retainer holding body 5 includes a cylindrical portion 50 having the inside diameter almost similar to the outside diameter of an annular projection 18 of the fitting main body 1. The retainers 3 and 4 are respectively energized in the mutually approaching direction by the spring 6. As a result, the flexible tube can be connected to the fitting by inserting the flexible tube in the connecting hole thereby fastening it by the fastening member.