To surely know the leakage of liquid-state substance even when the leakage of that liquid-state substance is a little by providing a detection sensor between an outer bag and an inner bag on the inner bottom part of that outer bag and providing an alarm means for reporting the leakage of liquid-state substance from the inner bag corresponding to a detection signal from this detection sensor.

A water bag 7 is formed in the shape of bag from a soft material such as a rubber sheet not to permeate any liquid-state substance, an inner bag 8a housing a liquid-state substance L is provided inside, and this inner bag 8a is housed in an outer bag 8b. Then, between the outer surface of the bottom part of that inner bag 8a and the inner surface of the bottom part of the outer bag 8b, a detection sensor 22 is provided for detecting the liquid- state substance leaked from the inner bag 8a. A cord 23 connected to this detection sensor 22 is liquid-tightly derived through a seal cock 24 provided on the side wall of outer bag 8b to the outside, and connected to a controller. As a power source and the alarm means, a buzzer is connected to this controller and corresponding to the detection signal from the detection sensor 22, the leakage of liquid from the inner bag 8a is reported.