PROBLEM TO BE SOLVED: To provide a bag-shaped structure capable of suppressing expansion of a lateral wall section and improving blood vessel compression properties.SOLUTION: A bag-shaped structure 32 to be used in a cuff 12 of a blood pressure-measuring device 1 is wrapped around a living organism 100, and applies pressure to the living organism 100 by expanding as a result of a fluid being supplied to an interior space thereof. The bag-shaped structure comprises: an inner wall section 41 provided on the living organism 100 side； an outer wall section 42 which faces the inner wall section 41； a pair of lateral wall sections 43 which are provided to be contiguous with the inner wall section 41 and the outer wall section 42, and have a curved section 43a which curves toward the interior space； and a reinforcing member 44 which tracks the shape in the living organism 100 winding direction, exhibits a greater hardness than the lateral wall sections 43, and is provided on the pair of lateral wall sections 43.SELECTED DRAWING: Figure 2【課題】側壁部の膨張を抑制し、血管圧迫特性を向上させることができる袋状構造体を提供すること。【解決手段】生体１００に巻き付けられ、内部空間に流体が供給されることで膨張し、生体１００を圧迫する血圧計１用のカフ１２に用いられる袋状構造体３２であって、生体１００側に設けられる内壁部４１と、内壁部４１に対向する外壁部４２と、内壁部４１及び外壁部４２に連続して設けられ、内部空間に向かって曲折された曲折部４３ａを有する一対の側壁部４３と、一対の側壁部４３に設けられ、側壁部４３よりも高い硬度を有するとともに、生体１００への巻き付け方向に対する形状追従性を有する補強部材４４と、を備える。【選択図】 図２
