Abstract: To provide a multilayer film for a disposable body warmer outer bag, and a disposable body warmer that are excellent in gas barrier property which inhibits permeation of oxygen gas, water vapor and the like, and that can allow swelling due to hydrogen gas generated during a storage period to be prevented. In a disposable body warmer outer bag formed from a multilayer film including a sealant layer 10 and a barrier layer 20, the sealant layer 10 and the barrier layer 20 serve as an inner surface and an outer surface of the outer bag, respectively. The sealant layer 10 includes a vapor-deposited layer 12 made by vapor-depositing a metal or metal oxide on at least one surface (upper portion in FIG. 1) of a thermal fusible resin substrate 11. The barrier layer 20 includes a polyvinylidene chloride layer 22 made by coating at least one surface (lower portion in FIG. 1) of a heat-resistant resin substrate 21 with polyvinylidene chloride.