To provide a method for producing a thermally cooked food having a water activity of ≥0.80 and imparted with a desired preservability by thermal sterilization with little loss using a simple procedure by using an acidulant coated with a scarcely water-soluble substance.

A thermally cooked food having a water activity of ≥0.80 and imparted with a desired palatability, taste and preservability is easily produced by mixing an acidulant coated with a scarcely water-soluble substance in the production of a thermally cooking food dough having a water activity of ≥0.80 and subjecting the mixture to heat-treatment to effect the thermal cooking as well as thermal sterilization and develop the effect of the acidulant coated with the scarcely water-soluble substance.