A method for producing a biodegradable bag and for packing a food, such as a snack food, which is required to have an oxygen barrier property and a water vapor barrier property. The biodegradable bag can be produced at a high speed by a bag making and packaging machine, which can be degraded by naturally occurring microorganisms in soil or water finally to a non-hazardous degradation product, which can be biorecycled, and which is not accumulated in nature. The biodegradable bag for packing a food comprises a laminated film obtainable by laminating in the following order: a sealant layer comprising a biodegradable polymer; a barrier layer having an oxygen barrier property and a water vapor barrier property; and a barrier layer-supporting substrate layer comprising a biodegradable polymer, the laminated film being heat-sealed in order for the sealant layer to be inside.