A fluid container unit including: a container coupling for coupling a supply/discharge port of a first container with a supply/discharge port of a second container; a single nozzle member having a nozzle tube; a connection cap having a first end for holding a base portion of the nozzle member and a second end for covering one side of the container coupling by fitting around an outer periphery thereof; an intermediate adaptor having a pair of pusher elements facing the first and the second supply/discharge ports, respectively; and a supply/discharge port opening mechanism for moving the intermediate adaptor toward the container coupling and opening the supply/discharge ports by the pusher elements. The pusher elements are movably held in a direction along a longitudinal axis of the nozzle tube in the connection cap.