A cooling unit has a member-to-be-cooled, a duct, and a cushioning material. The member-to-be-cooled has a plurality of cooling fins. The duct is fixed to the member-to-be-cooled, has a partition wall facing the plurality of cooling fins, and conveys a fluid to around the plurality of cooling fins. The cushioning material is disposed between the partition wall and the plurality of cooling fins and fixed to the partition wall.