A heat sink (1) for power module is capable of mounting a power device (101) on at least a surface of the heat sink. The heat sink includes a refrigerant passage (1d) in which cooling medium that dissipates heat generated by the power device (101) flows and a corrugated fin body (1a) arranged in the refrigerant passage (1d). The corrugated fin body (1a) has crests (21b) and troughs (21c) that extend in the flow direction of the cooling medium, and side walls (21a) each of which connects the corresponding one of the crests (21b) with the adjacent one of the troughs (21c). Each adjacent pair of the side walls (21a) and the corresponding one of the crests (21b) or the corresponding one of the troughs (21c) arranged between the adjacent side walls (21a) form a fin (21). Each of the side walls (21a) has a louver (31) that operates to, at least, rotate the cooling medium flowing in the associated fin (21). The heat sink (1) thus has a further improved heat dissipating performance.