Even with a plurality of heat exchange function surface units, a heat exchanger (1) can suppress an influence of the gravity exerted on refrigerant and suppress reduction of heat exchange performance in each of the surfaces. The heat exchanger (1) has the plurality of heat exchange function surface units (3), and includes an upper header pipe (5), a lower header pipe (7), and a plurality of heat exchange pipes (9) provided between the pair of upper and lower header pipes in each of the heat exchange function surface units. The plurality of heat exchange function surface units have a parallel connection relationship, and a plurality of the lower header pipes are connected to a lower collection pipe (19) through a branch current adjusting section (17).