There is provided an oxygen absorbing agent that can have a capability of absorbing oxygen in an atmosphere even when the atmosphere is free or substantially free from moisture. The oxygen absorbing agent comprises a metal, the metal having been obtained by subjecting an alloy comprising (A) at least one transition metal selected from the group consisting of manganese, iron, platinum, and copper group metals and (B) at least one metal selected from the group consisting of aluminum, zinc, tin, lead, magnesium, and silicon to treatment with an acidic or alkaline aqueous solution to elute and remove at least a part of the component (B).