Abstract: The heat source 1 comprises a bag 10 and a heat-generating composition 20 containing aluminum powder, calcium hydroxide powder and calcium oxide powder, enclosed in the bag 10. The bag 10 is formed by a packing material made of a base material of nonwoven fabric of which one surface is laminated with a watertight layer. The packing material is punched with a plurality of pinholes and has a water permeable rate of 13 to 81 milliliter/min/1 cm2 measured when head of water is 27 cm. The heat source 1 can satisfy preferable heating conditions including rate of temperature rise of the food, risen temperature of the food, duration of the risen temperature of the food under conditions in which a food heating device is conventionally used. Accordingly, a food heating device using the heat source capable of causing a rapid and stable heat-generating reaction can be provided.

Abstract: The heat source 1 comprises a bag 10 and a heat-generating composition 20 containing aluminum powder and calcium oxide powder, packed in the bag 10. The bag 10 is formed by a packing material made of a base material of nonwoven fabric of which one surface is coated with a watertight layer. The packing material being punctured with a plurality of pinholes and has a water permeable rate of 45 to 310 milliliter/min/1 cm2 measured when head of water is 27 cm. The heat source 1 can satisfy preferable temperature conditions including rate of water temperature rise, risen temperature of the water, duration of the risen temperature of water, rate of vapor temperature rise, risen temperature of the vapor and duration of the risen temperature of vapor under conditions in which a heating device is conventionally used. Accordingly, a heat source capable of causing a rapid and stable heat-generating reaction and a heating device using the heat source can be provided.