A flexible package which exhibits improved shape retention and improved self-supporting properties is provided. This flexible package is a package obtained by stacking at least first and second sidewall films and forming a storing space by sealing the stacked sidewall films in the peripheral area, wherein: a non-sealed area is provided in at least one of the two edge zones which are sealed areas formed by sealing the stacked first and second sidewall films in the peripheral areas in both edges, said non-sealed area being surrounded by the sealed area and extending over a prescribed length; a gas-filled part into which a gas exhibiting a specific heat at constant volume of 0.67kJ/kg-deg or more at 00C and 1 atm has been injected is formed in the non-sealed area; the gas-filled part has a diameter of 3 to 50mm; and the gas-filled part exhibits a repulsive force of 4 to 30N at 230C and 1atm as determined by pinching the whole of the gas-filled part from the first and second sidewall film sides and crushing the gas-filled part until the pinching width reaches half of the diameter of the gas-filled part.
