Al–Fe–Mn alloy processed by cold rolling is hardened by low temperature annealing. This behavior has been known as low temperature anneal-hardening in copper industry. In this study, we investigated the change of material properties and microstructures during low temperature annealing on cold rolled Al–Fe–Mn alloy with over 80% reduction. Al–Fe alloy, without Mn, was not hardened by low temperature annealing. As the cold rolling reduction of the specimen was higher, the tensile strength and the 0.2% proof stress increased by annealing. In anneal-hardened Al–Fe–Mn alloy, no precipitation was founded from the TEM observation, and no peak could be found on the DSC curve. Although the grain structure of Al–Fe–Mn alloy was refined by cold rolling, the dislocation density inside grain was low. This anneal hardening is similar to Hardening by annealing reported on severe deformation processing of aluminum.