PURPOSE: To make the outward evolution of air remaining in a space between joints possible by holding valve bodies at both tube ends through a spring provided at a support end to form a channel with the valve bodies pushing mutually when tube fittings are connected.

CONSTITUTION: Fittings are formed of a female joint 20 and a male joint 21, and connected through a nut 3. When the nut 3 begins to connect the joints 20, 21, a female valve 4 and a male valve 5 come into contact with each other to begin to form a channel. The nut 3 is further fastened to make the valves 4, 5 push mutually, resulting in gaps between a female body 1 and a packing 13, and a male body 2 and a packing 14 respectively to form the channel. Thus fluid in the fittings begins to flow.