A welding method to be executed by a welding system, wherein identification signs (Q) are arranged on a plurality of original workpieces (Wk1, Wk2) to be used in a welding process, respectively, the identification signs (Q) on which identifiers of the respective original workpieces (Wk1, Wk2) are readable, wherein each of the identifiers comprises a combination of a plurality of character codes, the welding method characterized in that : executing the welding process such that a part or an entire of an identification sign (Q) is hidden in a joint surface on which the plurality of original workpieces (Wk1, Wk2) are joined in the welding process, selecting, according to a predetermined rule, any one of the identifiers of the plurality of original workpieces (Wk1, Wk2) to be adopted as an identifier of a welded workpiece to be produced in the welding process; executing, after the selection, the welding process so as to hide a part or an entire of an identification sign (Q) of an original workpiece (Wk1, Wk2) having an identifier that has not been selected as the identifier of the welded workpiece, reading the identification signs (Q) assigned to the respective original workpieces (Wk1, Wk2) to be used in production of the welded workpiece; and generating and storing of welding process logical data indicating a relationship between the identifier that has been selected and the identifier that has not been selected. wherein identification signs (Q) are arranged on a plurality of original workpieces (Wk1, Wk2) to be used in a welding process, respectively, the identification signs (Q) on which identifiers of the respective original workpieces (Wk1, Wk2) are readable, wherein each of the identifiers comprises a combination of a plurality of character codes, the welding method characterized in that : executing the welding process such that a part or an entire of an identification sign (Q) is hidden in a joint surface on which the plurality of original workpieces (Wk1, Wk2) are joined in the welding process, selecting, according to a predetermined rule, any one of the identifiers of the plurality of original workpieces (Wk1, Wk2) to be adopted as an identifier of a welded workpiece to be produced in the welding process; executing, after the selection, the welding process so as to hide a part or an entire of an identification sign (Q) of an original workpiece (Wk1, Wk2) having an identifier that has not been selected as the identifier of the welded workpiece, reading the identification signs (Q) assigned to the respective original workpieces (Wk1, Wk2) to be used in production of the welded workpiece; and generating and storing of welding process logical data indicating a relationship between the identifier that has been selected and the identifier that has not been selected. executing the welding process such that a part or an entire of an identification sign (Q) is hidden in a joint surface on which the plurality of original workpieces (Wk1, Wk2) are joined in the welding process, selecting, according to a predetermined rule, any one of the identifiers of the plurality of original workpieces (Wk1, Wk2) to be adopted as an identifier of a welded workpiece to be produced in the welding process; executing, after the selection, the welding process so as to hide a part or an entire of an identification sign (Q) of an original workpiece (Wk1, Wk2) having an identifier that has not been selected as the identifier of the welded workpiece, reading the identification signs (Q) assigned to the respective original workpieces (Wk1, Wk2) to be used in production of the welded workpiece; and generating and storing of welding process logical data indicating a relationship between the identifier that has been selected and the identifier that has not been selected. <EOS>