To provide a fluid cushion which is capable of suppressing the moisture transpiration from the water sealed into a bag or liquid fluid containing the water and announcing the life of the bag.

The bag comprises the water or the liquid fluid 20 containing the water included in the bag elastically supported from an inner side and organic fatty oil 30 included in the bag. The organic fatty oil 30 has the nature that the organic fatty oil more hardly permeates the material of the top surface 11A of the bag than the liquid fluid 20 and since this organic fatty oil is lower in specific gravity than the liquid fluid, the organic fatty oil exists between the top surface 11A and the liquid fluid 20 within the bag and forms the layer of the organic fatty oil 30 along the front surface on the inner side of the top surface 11A. The bacteria to biodegrade the organic fatty oil 30 is mixed in the organic fatty oil 30, by which the organic fatty oil 30 is rapidly biodegraded at the prescribed point of the time before lapse of the period when the bag is usable without failure.