The present invention relates to a drainage bag and, specifically, to a drainage bag used for sucking and collecting: an effusion remaining in the body such as blood, lymph, pus, exudate and secretion or the drainage of the gastrointestinal tract. The present invention comprises: a bag main body comprising an upper storage part and a lower storage part, which are divided by a boundary partition at the middle part, wherein the upper storage part first stores, in the upper part, a secretion or drainage to be generated in the body and the lower storage part discharges the secretion or drainage to the lower part by the pressure of the upper storage part so as to store the same as the secretion or drainage increases at the upper storage part and comprises a discharge hole at the lower part, and the bag main body comprises a valve which is opened when the upper storage part is expanded through the inflow of the secretion or drainage, thereby allowing the secretion or drainage of the upper storage part to flow into the lower storage part and a tube coupled to the upper end of the upper storage part and guiding the secretion or drainage to be generated in the body to the upper storage part. In addition, an air pump and an elastomer capable of promoting drainage discharge are included, and a tube capable of facilitating specimen collection or gastric irrigation is further included.La présente invention concerne un sac de drainage et, spécifiquement, un sac de drainage utilisé pour aspirer et recueillir un restant dépanchement dans le corps tel que sang, lymphe, pus, exsudat et sécrétion ou le drainage du tractus digestif. La présente invention comprend : un corps principal de sac constitué dune partie de stockage supérieure et dune partie de stockage inférieure qui sont divisées par une cloison de délimitation au niveau de la partie intermédiaire, la partie de stockage supérieure stocke dabord, dans la partie supérieure, une sécrétion ou drainage devant être généré dans le
