To provide a deoxidation coating agent which contains an organic deoxidation agent, a polyolefin resin having a specific composition and an aqueous medium, is excellent in coatability, and provides a coating film excellent in deoxidation function and in storage stability.

The deoxidation coating agent contains: an organic deoxidation agent; a polyolefin resin containing an olefin-based hydrocarbon unit and a unit having a quaternized amino group; and an aqueous medium. The content of the unit having the quaternized amino group is ≥0.1 and <10 mol% to 100 mol% of all structure units constituting the polyolefin resin. The unit having the quaternized amino group has a carbonyl group derived from an unsaturated carboxylic acid unit or an unsaturated carboxylic acid anhydride unit.