The present invention is to provide wearing articles adapted to be identified one from another in one and same articles on the basis of a pattern of seam arrays (17) differentiated for every one of the wearing articles belonging to one and same articles and to provide a seam welder used to form the seam arrays. Front side edges (16a) and rear side edges (16b) of a diaper (1) are respectively joined by seam arrays extending in a longitudinal direction Y and thereupon a waist-opening and a pair of leg-openings are formed. The diaper comprises an inner sheet (18), an outer sheet (19) and a liquid-absorbent core (20) sandwiched between these inner and outer sheets. The inner and outer sheets are formed of heat-sealable fibrous nonwoven fabrics containing thermoplastic synthetic resins. Each of the seam arrays of the diaper comprises a plurality of seam-welded regions (21) and a seam-nonwelded region (22) left behind in the seam array. In the seam array, the seam-welded regions arranged so as to be aligned in longitudinal and transverse directions, each substantially shaped in a square, partially lack at a position differentiated for every one of specified patterns.
