PROBLEM TO BE SOLVED: To prevent Maillard reaction between amino acid and reducing sugar to suppress change with aging such as browning, resulting in increasing in keeping quality by storing a transfusion filled in a first medical vessel into an air impermeable second vessel with an oxygen scavenger. SOLUTION: A transfusion containing amino acid, reducing sugar, and electrolyte is filled in one air permeable first medical vessel to form a bag transfusion, the transfusion in the first medical vessel is stored in an air impermeable second vessel with an oxygen scavenger to prevent Maillard reaction between amino acid and reducing sugar. A three-layer laminate film bag body 1 in which a 15μm-thick biaxial oriented vinylon film and a 60μm-thick polyethylene film are laminated in this order is formed in such a manner that laminate polyethylene film is exposed inwardly and its circumference edge is welded with a heat seal 4, and the transfusion 2 in the bag and the oxygen scavenger 4 are stored and sealed in the bag 1.