To connect tubes without using a tool and to prevent the unnecessary rotary torque by constituting it of a screw member mounted on a tube end, and a transmitting member having a contact part with the screw member, and transmitting the rotary torque to the screw member, and providing the screw member with a thinned part in its rotating peripheral direction.

An end of a water supply pipe 3 is provided with a connecting member 10 having a seal member and engaged with an inside of a water supply port 5, and a screw member 11 having a threaded part 8 to be engaged with a threaded groove formed on an end of the water supply port 5. A transmitting member 9 is mounted in such manner that it covers the screw member 11. The screw member 11 is a molding made of polypropylene, and is provided with a thinned part capable of easily broken by the excess rotary torque, on its outside in the rotating peripheral direction. The threaded part 8 is formed inside in the rotating peripheral direction. Similarly, the transmitting member 9 is a molding made of polypropylene, and is contacted with the screw member 11 at its contact part 16, and the screw member 11 is indirectly rotated by rotating the transmitting member 9.