PURPOSE: To obtain a multi-layer bent pipe in which an inner pipe and an outer pipe is fitted firmly by forming the outer pipe as one body against the inner pipe by drawing, heating them, and thereafter, cooling the inner pipe, first, and subsequently, bending the multi-layer pipe by a bent arm in a state that the outer pipe is cooled.

CONSTITUTION: The outside peripheral surface of an outer pipe 2 which is superposed relatively with a gap 3 on an inner pipe 1 is heated by a burner, etc. 9 and it is fed into a drawing die 10. Subsequently, by cooling water 12 supplied from a water tank 13 to the inside of the inner pipe to the vicinity of the lower end of the die 10, a double pipe 4 which has passed through the die 10 is cooled from the inside. Simultaneously, the pipe 4 is cooled from the outside surface by cooling water sprayed from a nozzle 15 to the outside peripheral surface of the pipe 4 in a lower position than a water surface level of the cooling water 12 with which the inner pipe 1 is filled. Next, by bending the pipe 4 by a bent arm, while executing this cooling, a multi-layer bent pipe 14 is obtained. The multi-layer bent pipe concerned 14 has large resistance against stress corrosion cracking, and especially, it is suitable for an oil well pipe, etc. used in a corrosive environment.