PURPOSE: To obtain an excellent deoxidation accelerating effect by using an oxyacid salt contg. halogen as an electrolyte in a deoxidizing agent consisting of a combination of a metallic component having deoxidizing activity and an electrolyte component.

CONSTITUTION: An oxyacid salt (e.g. sodium perchlorate) contg. halogen is used as an electrolyte in a deoxidizing agent consisting of a combination of a metallic component (e.g. iron) having deoxidizing activity and the electrolyte component. Although the use of the oxyacid salt contg. halogen is not specifically restricted, 0.001W100pts.wt., preferably 0.01W10pts.wt., oxyacid salt is used basing on 100pts.wt. metallic component. Since the deoxidizing agent reacts easily with molecular oxygen in the presence of moisture, the agent reacts with molecular oxygen due to the action of steam discharged from food stuffs in a package. And the oxygen concn. in the package can be reduced to ≤1%.