The fluid container unit comprising: 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 one end for holding a base portion of the nozzle member and an other 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 to the first and the second supply/discharge port respectively, and being held movably in a direction along a longitudinal axis of the nozzle tube in the connection cap, 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. Thereby, in configuring a fluid container unit by integrally-assembling two containers for respectively accumulating different kinds of fluids in a parallel arrangement, the workability in fixing the fluid container unit to an injection site of a fluid usage equipment is improved, and the injection site can be configured to be more compact.