Stretchable sheet, worn article using the same, and stretchable sheet manufacturing apparatus

A stretchable sheet comprising:

• a pair of sheets whose first surfaces oppose each other or are in contact with each other;
• a plurality of elastic members that are arranged between the first surfaces of the pair of sheets and are arranged spaced apart from each other;
• a plurality of attached portions, wherein the first surfaces of the pair of sheets are attached to each other by a welding construction without using an adhesive, at the attached portions;
• the attached portions hold the elastic members;
• the attached portions extend in a direction crossing a direction of stretch of the elastic members;
• and the attached portions are spaced apart from each other in the direction of stretch between adjacent elastic members of the elastic members;
• and
• a plurality of folds that appear between the attached portions in a state where the elastic members are shrunk,
• wherein the attached portions include:
• a plurality of strongly-attached portions arranged on opposite sides of each of the elastic members in the crossing direction;
• and
• a plurality of weakly-attached portions;
• each of the weakly-attached portions being arranged between adjacent elastic members of the elastic members and between adjacent strongly-attached portions of the strongly-attached portions,
• wherein a strength of attachment between the pair of sheets at the weakly-attached portions is less than a strength of attachment between the pair of sheets at the strongly-attached portions.