To provide a suction system and a treatment method capable of effectively removing an object flowing in a living body lumen and providing a stable procedure.SOLUTION: A suction device 1 inserted into a blood vessel for collecting thrombus 300 in the blood vessel includes: a long-sized shaft part 24； an expansion part 20 which is an elastically deformable cylindrical body having a plurality of gaps 21A, and in which an outer diameter of the central part is larger than the end on both sides of the cylindrical body in a natural state in which no external force is applied； a proximal side connection part 60 provided to the proximal side of the expansion part 20； and a suction catheter 30 for movably storing the shaft part 24 and applying suction force. The suction catheter 30 includes a distal side opening 36 that the proximal side connection part 60 comes in contact with or enters, and an opening area of a suction hole 37 is larger than a cross sectional area of the suction lumen 30.SELECTED DRAWING: Figure 8【課題】生体管腔内を流れる物体を効果的に除去でき、かつ安定した手技を提供できる吸引システムおよび処置方法を提供する。【解決手段】血管内に挿入されて当該血管内の血栓３００を捕集するための吸引システム１であって、長尺なシャフト部２４と、複数の間隙２１Ａを備えて弾性的に変形可能な筒体であり、外力の作用しない自然状態において筒体の両側の端部よりも中央部の外径が大きい拡張部２０と、拡張部２０の近位側に設けられる近位側連結部６０と、シャフト部２４を移動可能に収容するとともに吸引力を作用させる吸引カテーテル３０と、を有し、吸引カテーテル３０は、近位側連結部６０が当接または入り込む遠位側開口部３６を有し、吸引孔３７の開口面積は吸引ルーメン３０の断面積よりも大きい。【選択図】図８
