Welding method for structure of low residual stress

A shape of an objective structural member to be welded (for example, a reactor core shroud of a pressure vessel of a BWR type reactor) is determined. Information including the material of the structural member to be welded and the kind of a bevel of a joint are inputted to a calculation control means. Then, information including the posture of welding, the diameter of a welding rod, and input heat amount are inputted. The build-up sequence of the welding passes is selected. Residual stresses due to the welding is analyzed for the structural members to be welded at the selected build-up sequence of the welding passes. The value of residual stresses at a noted point is compared with a value of residual stresses at noted points analyzed so far. When the value of the residual stresses at the noted point is smaller than the value of residual stresses at noted points analyzed so far, the build-up sequence of the welding passes evaluated this time is memorized. Welding condition with small residual stresses and residual deformation is thus determined. (I.N.)