A coinfusion apparatus including a coinfusion operation section a coinfusion processing room a supply section and a transfusion bag retention section. The coinfusion operation section consists of first and second robot arms. The first robot arm retains a medical agent container. The second robot arm performs an operation to insert a syringe needle of a syringe to a mouth section of the medical agent container and an operation to insert the syringe needle of the syringe to a coinfusion mouth of the transfusion bag. The coinfusion processing room holds the coinfusion operation section. The supply section supplies the medical agent container and the syringe into the coinfusion processing room. The transfusion bag retention section retains the transfusion bag at the outer side of the coinfusion processing room and positions the coinfusion mouth of the transfusion bag at the coinfusion communication mouth formed in the coinfusion processing room.
