PURPOSE: To actively restrain generation of cracks by welding an outer circumferential surface of a pipe body in the inserted state into a socket hole of a socket and then, forming an additional welded bead on the outer circumferential surface of the socket and at the position separated from the end surface.

CONSTITUTION: An outer circumferential surface of a pipe body 3 in the inserted state into a socket hole 5 of a socket 2 and the end surface of the socket 2 are welded together and then, an additional welded bead 6 is formed in the ring state on the outer circumferential surface of the socket 2 and at the position separated from the end surface by a distance 1. The forming condition of this additional welded bead 6 is that the distance 1 between the end surface and the center of the bead 6 has the relation of an equation I when the outer diameter of the socket is d and the plate thickness of the socket hole wall is t, and welding heat gain per 1cm plate thickness shall be in the range of 7 to 15 kiro joule/cm. When the bead 6 is formed under this condition, even in the case where tensile residual stress easily acts at the position on the inner surface of the socket hole 5 and in the neighborhood of a welded part 4, generation of fatigue cracks in this portion can be prevented by moving it in the direction of compressed residual stress.