PURPOSE: To improve the corrosion resistance of the external tube surface of a heat exchanger made of A1 consisting of a combination of a fin and a tube having a brazing filler metal layer on the external tube surface, such as radiator and parallel flow type capacitor.

CONSTITUTION: The heat exchanger made of Al is produced by using, as a fin material, a bare material of Al alloy containing ≥0.5% Zn, also using, as a tube material, a brazing sheet, where at least the side, to be the outer side of a tube, of an Al alloy core material is clad with an Al-Si brazing filler metal to ≥15μm thickness, assembling a heat exchanger, applying a fluoride type flux, drying this flux, and then exerting brazing in a nonoxidizing atmosphere.