To prevent vanes from being broken in a strong wind by stopping the rotation of a windmill and to provide the installation and the maintenance with convenience by lowering the vanes and raising a cam tube in the string wind, by directly interlocking the movement of a tail unit to the vanes, and setting the vane faces in parallel to the wind.

A wind direction tail unit 4 is installed to a vane rotary shaft end with its shaft concentric to the vane shaft 2 and the rotation of the rail unit 4 is transmitted to the vane 1, for example, at the rate of 2:1. The vane shaft 2 is extended to a position of the wind direction tail unit 4 using a double shaft and the rotation of the tail unit 4 to the vane 1 is, for example, transmitted to 1:1 so that the movement of the tail unit 4 and the vane 1 is directly interlocked, and all the vanes 1 are set parallel to the wind direction in the strong wind so as to eliminate the generation of the rotating force and stop the rotation of the windmill. Generally in operating, the cam tube is in contact with a pulley end and the wind direction response mechanism is functioned, however in the string wind, the cam tube is moved so that the tail unit shaft and the vane shaft 2 are connected to each other and the direction of the tail unit 4 and the direction of the vane faces are coincided together so as to resist against the wind.