A plurality of fin groups 12 each comprising parallel plate fins 14 are arranged on two straight tube portions 11a of a fin fixing hairpin tube 11 longitudinally of the tube portions at a spacing, by forming two tube inserting holes 14a as spaced apart in each of the plate fins 14 and inserting the two straight tube portions 11a through the respective holes 14a of the plate fins 14. The hairpin tube 11 is enlarged with use of a fluid to fixedly fit the plate fins 14 of the fin groups 12 around the straight tube portions 11a of the tube 11. The straight tube portions 11a of the tube 11 each have a finless part 13 provided between each pair of adjacent fin groups 12. The finless part 13 of each straight tube portion 11a bears clamp marks 19 on the outer peripheral surface thereof. A heat exchanger comprising a heat exchanger finned tube 10 thus constructed is adapted to diminish leakage of the refrigerant and achieves a desired refrigeration efficiency.