The fit of a flexible sheet is assured by an elastic member, while maintaining a high degree of flexibility. The elastic material around the legs, which is attached at the front (F) or the back (B) of the exterior sheet (20), or on both sides, and bends and flexes along the leg openings, has straight, non-adhesive parts, which are not attached to the exterior sheet, that are sandwiched by a pair of adhesive parts that are attached to the exterior sheet.
