A joint for duplex storage type fluid container that can attain secure fitting of a liquid discharge tube and can attain easy, secure connection of a passage for fluid emission disposed in a dispenser to the liquid discharge tube. There is provided a joint for fluid container comprising flexible bag (12) furnished with neck part (11) openable for permitting injection of liquid and comprising outside container (13) formed so as to support the neck part (11) by mouth part (13a) and accommodate the bag (12), which joint is so structured that liquid discharge tube (15) with collar part (15a) can be fitted through plug (14) to the mouth part (13a) of the outside container (13), and further so structured that flow channel (21a) fitted to dispenser (2) can be linked directly to fluid passage (15b) of the liquid discharge tube (15).