To enhance a heat exchanging performance by assuring a brazing connection of a header pipe to a tube and preventing a leakage of a heating medium in a heat exchanger mainly having the header pipe, the tube and fins.

Parallel part parallel to a tube surface is provided at connecting part of the fin to the tube, folding parts each folded at an angle of θ to the parallel part are provided at both ends of the parallel parts, and fins of sectional shapes having rising parts substantially perpendicular to a tube surface are provided at the other ends of the folding parts. The angle θ formed between the parallel part and the folding part is preferred to be about 5 to 30 degrees. A length of the parallel part is preferred to be 0.1 to 0.4 times as large as a pitch of the fins.