PURPOSE: To reduce residual stress on a corner part after clad welding than that on other parts by increasing the substantial heat gain of the corner part than that of peripheral other parts with respect to clad build-up welding on the nozzle inside of a pressure vessel, etc.

CONSTITUTION: Clad material 4 is subjected to build-up welding all over the surface in the form to cover base metal 3 from a standpoint of corrosion resistance on the inside of a nozzle 2 of a nuclear reactor vessel, for instance. This clad material is clad built-up 5 continuously so as to wind in the circumferential direction on the nozzle part. In cladding of the corner part, even if the build-up thickness is the same as other parts, a heat-affected zone by welding is taken deeper in the direction of the base metal side thickness from other parts by operating the heat gain or the welding time. By this method, the residual stress generated after welding can be reduced and further, since the heat-affected zone has higher fracture toughness value than the base metal itself, it also becomes more advantageous in soundness from this point.