Icosahedral and decagonal quasicrystals with the same composition have been obtained in Al 70Pd 30− X ( X = 16, 17 and 18). The average magnetic moment 〈 P c〉, saturation moment M s, ratio of magnetic Mn atoms and spin glass have been investigated for both quasicrystals. The values of 〈 P c〉 and M s for the icosahedral phase are higher than those for the decagonal phase. The magnetic Mn atom ratio estimated from M c〉 and M s for the two types of quasicrystal is 11–14% (by Mn content) or about 2% (by total content). The formation of a giant magnetic moment due to the polarized d band of Pd is confirmed in the icosahedral phase. The spin glass behavior has been confirmed in both phases. The spin freezing temperature T f of the icosahedral phase is higher than that of the decagonal phase, implying that the magnetic interactions in the icosahedral phase are stronger than those in the decagonal phase. Furthermore, the Mn concentration dependence of T f for the former is steeper than that for the latter. From these results, it is clear that the magnetic properties of the icosahedral and decagonal phases are distinct, reflecting the different quasicrystalline structure.