An aluminum flat tube for a heat exchanger is fabricated from an aluminum strip-shaped material which is structured by a core material coated with a sacrificial anode material on the inner face thereof and coated with a brazing filler metal on the outer face thereof by bending in the width direction to form a nearly B-shaped flat cross section. To improve the corrosion resistance of the inner face of the tube, the both edge parts of the strip-shaped material in the width direction thereof are bent inward into the tube so as the front end edge of the edge part to become apart from the flat inner face of the tube.