Heating device

A steam direct heating device comprising:

• a heating container for generating a hot steam by an exothermic reaction sufficient to heat a cooked food and a food container housing the cooked food to be heated, having apertures in a portion of a bottom wall thereof for passing the hot steam and being positioned over the heating container, wherein the heating container has an opening on an upper side thereof;
• a first bag containing calcium oxide as exothermic materials and a second bag containing water, the first and second bags being located in the container and the first bag being positioned over the second bag;
• a sheet-type filter provided over the opening of the container, the filter preventing exothermic materials from leaving the container;
• and
• means for exposing the exothermic materials in the first bag to water in the second bag to thereby start an exothermic reaction releasing a high temperature steam, the steam passing through the sheet-type filter but the exothermic materials being prevented from passing through the filter even when the exothermic materials are conveyed by water splashing in the exothermic reaction.