The present invention provides an infusion vessel, which is capable of separately containing a drug and a infusion liquid in a sterile manner and mixing the drug with the infusion liquid in a sterile manner by a simple operation for use, while ensuring the sterility of a connector thereof. The infusion vessel according to the present invention comprises a bag (2) for containing a infusion liquid, a two-mouth vial (3) for containing a drug, and a joint (4) connecting the bag and the vial. A lower mouth portion (33) of the vial (3) is sealed with a rubber plug (7). The joint (4) is air-tightly connected to a liquid outlet port (21) provided in a bottom portion of the bag (2), and extends downward. The joint (4) has an opening (46) for communication between the inside and the outside thereof. An O-ring (6) and an intermediate rubber plug (5) are respectively attached to the joint (4) above and below the opening (46), and fitted in the upper mouth portion (32) of the vial (3) in an axially movable manner.