A wind driven electric power generator (1) in which the temperature inside a rotor head can be controlled. A wind impeller (5) is mounted on the rotor head (4). A drive and electric power generation mechanism is received in the nacelle (3) and connected to the rotor head (4). Control devices are received in a hub (7) of the rotor head (4). The generator (1) has an air circulation guide (20) for circulating air between the inside of the rotor head (4) and the inside of the nacelle (3) via a communication path (9) formed between the rotor head (4) and the nacelle (3).
