Provided is a multilayer film for a disposable body warmer outer bag, and a disposable body warmer, which are excellent in gas barrier property that inhibits permeation of oxygen gas, water vapor and the like, which can allow swelling due to hydrogen gas generated during a storage period to be prevented, and which are excellent in seal strength, impact resistance and weather resistance.A disposable body warmer outer bag formed from a multilayer film comprising a first barrier layer (10) and a second barrier layer (20), wherein the first barrier layer (10) and the second barrier layer (20) consist of a polyvinylidene chloride layer (12) or a polyvinylidene chloride layer (22) obtained by coating at least one surface (upper portion in FIG. 1) of a heat-resistant resin substrate (11) or a heat-resistant resin substrate (21) with polyvinylidene chloride.