Al-Mg alloy foams were synthesized via conventional melt foaming method. Ca and TiH2 were introduced into molten Al-Mg alloys with different magnesium contents. The macrostructures of resultant alloy foams were analyzed and correlated with compressive properties estimated by compression test. It is shown that the pore structures observed in alloy foams degraded with increasing Mg contents. This tendency was shown to be consistent with compressive characteristics of corresponding alloy foams. In detail, plateau strength was high for Al-1wt%Mg alloy foams, exhibiting a gradual decrease in plateau strength with increasing magnesium content.