The present work has been carried out focusing on changes of aging response by misch metal(Mm) addition in Al-Mg-Si alloys with excess Mg. With addition of Mm, precipitation of (Mg₂Si) phase and formation of clusters decreased and delayed. However, thermal-stability of precursor phases increased, which is considered as reasons for delayed aging response. Although strengthening precipitate decreased in Mm added Al-Mg-Si alloy with most excess Mg content, slight improvement of tensile properties was observed and it may be estimated that additional solid solution strengthening by excess Mg worked on strength in Mm added Al-Mg-Si alloys.