To provide a method of fixing an aluminum sash frame securing sufficient yield strength against strong wind pressure, easily securing quality after construction by dry fixing, shortening a construction period and reducing construction cost.

A first base fitting 5 is fixed to an RC constructed rising part 4 constituting the lower side of an opening of a building skeleton, and a first fastener fitting 6 is fixed to the first base fitting 5 by welding. A second fastener fitting 7 is fixed to a lower frame of the aluminum sash frame 1, and the second fastener fitting 7 and the first fastener fitting 6 are fixed in a swayable manner by a clamping bolt 11 and a nut 12. A second base fitting 14 is fixed to an ALC plate 13 constituting the upper side of the opening, and a third fastener fitting 15 is fixed to the second base fitting 14 by welding. A fourth fastener fitting 16 is fixed to an upper frame of the aluminum sash frame 1, and the fourth fastener fitting 16 and the third fastener fitting 15 are clamp-fixed by a clamping bolt 20 and a nut 21.