PURPOSE: To produce an Al-Mg-Si alloy excellent in intergranular corrosion resistance and used as a brazing sheet, an automobile body sheet or the like and to produce a brazing sheet using the same as a core material.

CONSTITUTION: An Al-Mg-Si alloy having compsn. contg., by weight%, 0.1 to 1.6% Mg, 0.2 to 2.0% Si, 0.01 to 0.5% Bi, and the balance substantially Al is furthermore added with one or more kinds selected from among Cu, Ti, Mn, Cr and Zr. Preferably, the Al-Mg-Si alloy for brazing having compsn. contg., by weight%, 0.1 to 1.0% Mg, 0.2 to 1.2% Si, 0.01 to 0.5% Bi, and the balance substantially Al is prepd. In the same alloy for brazing, one or more kinds selected from among Cu, Ti, Mn, Cr and Zr are moreover added thereto. Zn is added thereto as well. Furthermore, the grain size of Bi is regulated to 1 to 20μm, and the density thereof is regulated to 40 to 2000 pieces/mm2.