In a wind generator, which effectively utilizes an opening of a door opening and a shell plate, and in which an outside air-circulation flow path for introducing outside air into a cooling heat exchanger in a tower is formed, a cooling medium that cools a heating element disposed in the tower circulates through a cooling heat exchanger, and heat is absorbed by exchanging heat with outside air, an outside air-circulation flow path of a closed space having an outside-air inflow opening and an outside-air discharge opening that are in communication with a door opening of a shell plate is formed in an interior space in the tower, and the cooling heat exchanger is disposed in the outside air-circulation flow path.