To provide an aluminum heat exchanger in which a brazing filler metal 2 is covered on an outer circumferential surface of a core 1, an aluminum strip with a sacrifice anode 3 covered thereon is used for an inner surface side, the strip is bent in the width direction to form a flat tube 5, a large number of flat tubes 5 are arranged in parallel and brazed in a furnace by using flux, the brazing is excellently performed, and the strength after the brazing is high.

The brazing filler metal 2 is formed of Al-Si alloy, and the core 1 is formed of Al-Si alloy containing 0.4-1.2 wt.% Si. The sacrifice anode 3 is formed of Al-Mg-Zn alloy containing 0.3-0.75 wt.% Mg.