A container for a fluid includes a carton of a long hollow shape having an inner surface, and an inner bag attached to the inner surface of the carton for containing the fluid in it. The flexible inner bag has a fluid-discharge port. The inner bag is separated from the carton according to discharging of the fluid. The container also includes a separation detecting device. This device is disposed along a separating direction of the inner bag, which is separated according to taking out of the fluid.