Bag-shaped structure, blood pressure monitor cuff, and blood pressure monitor

A bag-shaped structure comprising:

• a first sheet member including a layer formed of a thermoplastic elastomer;
• and
• a second sheet member including a plurality of layers formed of a plurality of types of thermoplastic elastomers having different levels of hardness, wherein
• the second sheet member is joined with the first sheet member,
• a layer that is included in the plurality of layers of the second sheet member, and that is in contact with a living body, has a Shore A hardness higher than a Shore A hardness of at least one of the other layers of the second sheet member;
• and
• wherein the second sheet includes a first layer that is in contact with the living body, a second layer that is in contact with the first sheet member, and a third layer that is included between the first layer and the second layer, the third layer having a Shore A hardness lower than a Shore A hardness of the first and second layers.