The ultrafine-grained Al 6061 alloy, which was fabricated by the combination of cryogenic rolling with warm rolling, achieved high ultimate tensile strength of 420 MPa. Compared with the results by other severe plastic deformation methods, the strengthening effect by the combination of cryogenic rolling with warm rolling was found significantly effective. This notable increase of tensile strength was achieved by the formation of finer precipitates during warm rolling. The presence fine precipitates of diameter below 100 nm, in ultrafine-grained matrix, were confirmed with TEM and STEM. The estimated precipitation strengthening by the fine precipitates was approximately 100 MPa. Based on the results, it was found that cryogenic rolling combined with warm rolling would be effective in increasing strength.