The super high strength Al-Zn-Mg based alloy Mesoalite20 ® with a chemical composition of Al-9.5Zn-3Mg-1.5Cu-4Mn-0.5Zr-0.02Ag in mass% includes two type of precipitates of Q and Al 6 Mn phases. The Q precipitates have a quaternary composition and fine rod-like shape, but Al 6 Mn has round and irregular shape. After compaction of air-atomized powder by CIP, the Q and Al 6 Mn phases precipitated in sequence during heating. By hot extrusion at 773 K, their precipitates flowed along extrusion direction and only Q precipitates aligned well, which have been known to be very effective to fiber-reinforcement. When increasing Mn content from 4 to 7 mass% with constant of 1.5 mass% Cu, the amount of Al 6 Mn increased remarkably. Consequently the compressive strength and plastic elongation to fracture decreased with increasing Mn content. When increasing Cu content from 0.5 to 2.5 mass% with constant of 4 mass% Mn, on the other hand, the amount of Q phase increased and their mechanical property improved slightly with increasing Cu content. Therefore the present study has proposed a new alloy with higher Cu content, which gives higher strength than that of commercial Mesoalite 20.