PURPOSE: To obtain an Al-Zn-Mg alloy hollow shape excellent in strength, bendability, SCC resistance, and corrosion resistance by forming the whole metallic structure into a structure in a state of fibers parallel to the direction of extrusion.

CONSTITUTION: An ingot of an Al-Zn-Mg alloy, which has a composition consisting of, by weight, 5.0-6.0% Zn, 1.2-1.8% Mg, 0.20-0.50% Cu, 0.10-0.50% Zr, Fe and Si by the amounts in the ranges where (Fe+Si) and (Fe/Si) are regulated to 0.10-0.60wt.% and ≥1.5, respectively, further 0.01-0.10% Mn and/or 0.01-0.10% Cr, and the balance essentially Al, is subjected to homogenizing treatment at 420-520°C for 2-24hr, extruded at 430-520°C, cooled down to room temp., and then subjected, as artificial ageing treatment, to first-stage heat treatment at 90-110°C for 2-12hr and to second-stage heat treatment at 120-170°C for 5-24hr.