A stretchable/contractible sheet having an up-down direction and a left-right direction intersecting each other includes a first sheet； a second sheet； welded portions； and elastic members. Elastic members are arranged between the first sheet and the second sheet by welded portions and with a space in the up-down direction. The welded portions include a first welded portion； and a third welded portion. The welded portions further include a second welded portion； and a fourth welded portion. The first welded portion and the third welded portion have portions that overlap in the up-down direction. A length of a portion where the first welded portion and the third welded portion overlap in the up-down direction is larger than a length in the up-down direction between a lowermost end of the first welded portion and a lowermost end of the third welded portion.
