To provide an oxygen-absorbing resin composition, which has adequate capability of absorbing oxygen in an atmosphere of low humidity and exhibits a reduced degree of generation of a gas other than oxygen when absorbing oxygen without causing the change in quality of a content, the lowering of flavor and the like, and also a multilayer packaging material using the resin composition.

The oxygen-absorbing resin composition comprises a thermoplastic resin having a water absorption of 1% or below, a reducing iron power having an average particle size of 10 to 50 μm, a specific surface area of 0.5 m2/g or over, and an apparent density of 2.2. g/cm3 or below, and sodium iodide. The reducing iron power should preferably be one that contains not less than 50% or over, based on the total particles, of flat particles having a degree of compaction of 20% or over and an aspect ratio of 0.75 or below.