Abstract: In a compact heat exchanger, a heat exchanger tube adapted for precision assembly of an outer tube and an inner tube and free from decreasing heat transfer efficiency is provided. For this purpose, the heat exchanger tube includes: a plurality of parallel outer tubes; inner tubes inserted in the outer tubes and having their opposite ends extended outward of the outer tubes; a gap support member formed of a wire material disposed in a gap between an inner periphery of the outer tube and an outer periphery of the inner tube and making spiral contact with the inner periphery and the outer periphery substantially throughout the length of the outer tube; and a supporting member making spiral contact with an inner periphery of the inner tube throughout the length of the inner tube.