A heat exchanger including a heat transfer fin (1) having a heat-transfer-tube insertion hole (10) through which a heat transfer tube (40) is inserted, and a brazing material holding portion (100) provided above the heat-transfer-tube insertion hole (10) to hold a brazing material (4), wherein when the heat transfer tube (40) is inserted through the heat-transfer-tube insertion hole (10), left and right non-contact portions (15), (16) where a circumferential edge of the heat-transfer-tube insertion hole (10) and an outer circumferential surface of the heat transfer tube (40) are not in contact with each other are separately formed on an upper circumferential edge of the heat-transfer-tube insertion hole (10), and a brazing material guiding portion (100) extending toward the outer circumferential surface of the heat transfer tube (40) is formed between the left and right non-contact portions (15), (16).