A disposable warmer of the present invention has a bag including a bag member (A) and a bag member (B) a heater a heat-sealed portion where the bag member (A) and the bag member (B) are heat-sealed and a portion with the heater sealed therein. The bag members (A) and (B) are heat-sealed with each other to form the bag, the bag member (A) includes at least a layered structure with a porous film and a nonwoven fabric layer, and the bag member (B) includes at least another layered structure with a stretchable film and another nonwoven fabric layer. The disposable warmer comprises two or more of the portions with the heaters sealed therein independently, and a slit in at least the porous film constituting the bag member (A) of the bag members (A) and (B) in at least one region between the adjacent portions with the heaters sealed therein.
