PURPOSE: To make it possible to prevent the putrefaction and deterioration of a raw feed and efficiently store the feed, by cutting off the circulation of air to a layer of the raw feed and inserting disoxidizing materials consisting essentially of iron powder absorbing oxygen into the raw feed layer.

CONSTITUTION: An air barrier film 5 is spread on a filled layer of a raw feed 3, e.g. corn, stored in a silo 2, etc., for cutting off the circulation of air to the layer of the raw feed 3. Weights 6 are then placed thereon. Disoxidizing materials 4 consisting essentially of iron powder absorbing oxygen are further inserted into the layer of the raw feed 3. This method is applicable also to an already constructed silo structure and the raw feed 3 can be efficiently stored while preventing the putrefaction and deterioration thereof without installing a new power source.