PURPOSE: To enhance the heat exchange capacity, by forming on one fin a plurality of portion having different widths with a draft resistance per row of the narrow portion being larger than a draft resistance per row of the wide portion.

CONSTITUTION: In a thin indoor unit including the heat exchanger 1, a through flow fan 2 and a dew receiver 4 in a cabinet 3, a row of the cross fin tube type heat exchanger 1 is formed into a slit fin and another right row is formed into a corrugated fin or the like. Thus, the draft resistance can be varied to improve the performance of the heat exchanger.