PURPOSE: To obtain a heat exchanger, etc., made of Al having excellent corrosion resistance by executing the heat treatment at a specific temperature and for a specified time after brazing.

CONSTITUTION: For example, a brazing sheet of 0.4mm thickness obtd. by cladding (clad ratio is 10% on one side) an Al-8Si-3Zn alloy brazing filler metal having a composition contg. 8wt.% Si, 3wt.% Zn, and the balance consisting of Al and inevitable impurities on both faces of a core metal of pure Al containing only inevitable impurities is prepared. A tube is composed by using this sheet. The tube and an Al fin are assembled, and these are brazed by using a fluoride base flux in the inert gas atmosphere. After that, the heat treatment is executed to the product for ≥3 minutes at the temperature of 100 to 400°C. Consequently, the Al base product having excellent corrosion resistance can be obtained.