PROBLEM TO BE SOLVED: To provide an underpants-type disposable diaper which achieves sufficient strength during wearing and can be teared off easily without impairing advantages of a horizontal striped pattern.SOLUTION: The underpants-type disposable diaper is characterized in that polypropylene regions 13P of waist edges W at side sealed parts 13 are weld-bonded in such a way that inner welded parts 13i having inner edges projecting further from the adjacent welded parts and outer welded parts 13s having outer edges projecting further from the adjacent welded parts are weld-bonded in an alternate pattern wherein the inner edges and outer edges are arranged alternately in the longitudinal direction.
