Microsegregation and its homegenization behavior of magnesium and silicon in Al-1, 1wt %Mg-0.68wt%Si alloy as well as those of chromium and titanium in the alloy have been investigated. Minimum magnesium and silicon concentrations in alpha-dendrite arm are 0.4wt% and 0.2wt% that are one half and one third of each composition, respectively. The concentrations are, however, rapidly homogenizecl at 530℃. Titanium and chromium elements make grain size be greatly refined in Al-Mg-Si alloys but they are remarkably concentrated at the center of alpha-dendrite arm and from a cored structure. The maximum concentrations increase two to three times for titanium and one and a half times for chromium. The concentration of titanium does not appear outside the cored structure but that of chromium is approximately one half of the total ahromium amount. These do not disappear at 530℃ for 100 hours. During homogenization treatment, chromium is deposited as E phase of Al_(18)Mg₃Cr₂ around crystallized compounds and its distribution becomes inhomogeneous.