A heat exchanger having a heat transfer tube (12), heat transfer fins (13a) arranged side by side in the direction crossing the axis of the heat transfer tube (12), and cut and turned up sections (14) provided on the heat transfer surface of each heat transfer fin (13a). At the lower end or at both the upper and lower ends of a cut and turned up section (14) are formed incisions extending in the longitudinal direction. The incisions guide condensed water produced on the surfaces of the heat transfer fins so that it flows downward.
