Provided is a multi-chamber bag which enables a user to accurately check a contained medicine without requiring a complicated work and which can prevent a material which degrades the medicine from reaching the medicine containing chamber and surely prevent degradation of the medicine. The multi-chamber bag includes a bag body having a strong seal portion and a weak seal portion. The strong seal portion has two sheet members bonded to each other to partition an internal space. The weak seal portion has sheet members detachably bonded to partition the internal space into a medicine containing chamber and a dilution liquid containing chamber. The multi-chamber bag includes a pair of cover sheets which cover the medicine containing chamber. Each of the cover sheets is bonded to an opposing sheet member forming an external seal portion surrounding the medicine containing chamber. The other cover sheet is configured so as to absorb a bad material. A communication portion is formed between the inner side edge of the outer seal unit and the inner side edge of the strong seal portion so as to communicate with the space between the sheet member and the cover sheet at the both ends.
