[Object] An object of the present invention is to provide an extremely practical and innovative food product heat treatment method capable of performing the same heat cooking and heat sterilization as that of the conventional technique while enhancing economy and productivity in comparison with the conventional technique. [Means of Achievement] The food product heat treatment method is characterized in comprising placing a food product (2) in a hermetically sealed vessel (1) in which a prescribed vapor pressure is maintained or can be maintained; injecting a heating liquid heated by a heating source (8) to 100.degree. C. or higher into a space in the hermetically sealed vessel (1) towards the food product; bringing the heating liquid injected in the hermetically sealed vessel (1) into contact with the food product (2), a food product package (3), or a cover body (4) of the food product (2) or food product package (3) rather than submerging the food product (2) in the heating liquid and performing heat treatment; and heat treating the food product (2) placed inside the hermetically sealed vessel (1), which is a hermetically sealed pressurized space, through heat of the heating liquid.