Abstract: A method for jointing two pipes such as an aluminum pipe and a copper pipe by friction welding. The aluminum pipe is inserted into a bore of a ring made of a heat resistant material, the bore having a straight section and a tapered section continuous from the straight section. The copper pipe has a tapered end peripheral surface. The copper pipe is pressed at its tapered end, in a rotating state, against the end of the aluminum pipe so as to expand the latter. As a result, an ironing is effected on the aluminum pipe by the straight section of the bore of the ring, such that the aluminum pipe overlies the straight section of the copper pipe in close contact with the latter. Consequently, the tapered surface of the copper pipe is friction welded to corresponding portion of the aluminum pipe while the latter is being backed up by the tapered section of the bore of the ring.