An object is to cool electrical components mounted to an automobile efficiently. A cooling device (1) for cooling a first member (2, 4) and a second member (3, 5), includes: a cooling medium flow passage (R) which is formed between the first member (2, 4) and the second member (3, 5), and through which a cooling medium for cooling the first member (2, 4) and the second member (3, 5) flows; and a swirl generation enhancing portion (51, 52, 53) disposed in the cooling medium flow passage (R) and configured to enhance generation of a swirl of the cooling medium flowing therein.