A heat exchange tube (4) is constituted of sheet members not covered with a brazing material layer, and a joint width (4d) where the sheet members are overlapped is brazed with a brazing material. The structure above reduces the possibility of spreading of the brazing material while the heat exchanger tube is being brazed and of dissolution of the tube by erosion. As a result, tube quality, such as corrosion resistance, is prevented from being affected by thinning of a tube material.