<p>A fluid container comprising a flexible bag (1) containing a diluent and having a closing film at its upper end, a capsule (2) connected to the flexible bag, a drug container (3) held in the capsule and a communicating means (16) communicating the flexible bag with the drug container. The communicating means has a double-edged hollow needle (7) having a hub in the midway thereof, and a controlling means (6) for controlling the order of communication in such a manner that the plug of the drug container is sticked with one edge of the needle and thereafter the closing film of the flexible bag is sticked with the other end of the needle. The mixing procedure is sure and simple, and can be carried out in a short time.</p>
