PURPOSE: To enable brazed joining with flux coating once and to shorten the process by forming the recessed part holding a flux along a joining part and executing brazing by holding brazing filler metal and flux inside the recessed part.

CONSTITUTION: The annular brazing filler metal 5 composed of a wire rod is fitted to one end part of a tube 1 along its outer periphery and its one end is fitted into a pierced stepped hole 3 from the end face of an union 2. On the size of this hole 3 the range of the depth A at the end face side of the union 2 is made slightly larger than the outer periphery of the tube 1 and the range of the depth B at the back part therefrom is taken in the size that the outer peripheral face of the rube 1 is brought into contact with the inner peripheral face of the stepped hole 3. This assembled part is dipped into the flux of an ordinary density to hold the necessary and enough flux 6 inside a recessed part 4. The flux in the necessary amt. can be thus coated at one stage and a good surface state can be obtd.