PURPOSE: To preserve a processed food without freezing them, by putting a heated processed food consisting essentially of wheat flour in a flat container with an open top, closing the open top with a film.

CONSTITUTION: In case of Okonomiyaki (a thin, flat cake of unsweetened batter fried with bits of vegetables), wheat flour is kneaded with water, blended with ingredients such as a cabbage, egg, lees of Tempura (japanese deep-fat fried food), retc. to give a batter, which is injected into the container 1. The ingredients 6 such as meat, etc. are placed on the wheat flour, and the periphery of synthetic resin film 3 is bonded to the whole surroundings of the flange 4 of the container 1 and sealed hermetically by heat sealing, etc. The sealed container 1 is heated by retort treatment or boiling, the batter is solidified and the ingredient 6 are heated, to give a packed instant food.