To provide a heat exchanger capable of improving capacity in condensation while lessening an increase in refrigerant pressure loss in evaporation by appropriately determining the arrangement of two or more kinds of heat exchanger tubes with different helix angles.

This heat exchanger has a heat exchanger tube 21a performing heat exchange by the condensation or evaporation of a refrigerant in the tube with a groove 33 spirally formed on the inner surface of the tube at a prescribed helix angle to the axis of the tube, and a fin 22 into which the heat exchanger tube 21a is inserted. In constituting the heat exchanger, a plurality of heat exchanger tubes 1-5 with different helix angles are connected, and the heat exchanger, tubes 3-5 with the large helix angles out of a plurality of connected heat exchanger tubes 1-5 are arranged on the small dryness side of the refrigerant rather than the large dryness side.