To repel the water drops attached to a side mirror by the centrifugal force, by mounting the blades around a rear face of a circular mirror, mounting a shaft and a bearing pedestal on a center of the rear face of the mirror for providing the mirror with a rotary function, and rotating the mirror by the wind force.

The blades 2 are sticked around a rear face of a circular wide angle mirror 1 like a wind mill, or a shaft 3 and a bearing pedestal 4 are vertically mounted on a center of the rear face of the mirror 1, and a flat washer 6, a spring washer 7 and a nut 8 are fastened through the bearing 5 to provide the mirror with a rotary function. The mirror with rotary function is mounted on an existing side mirror in the travelling in the rain by a sucker method of a clamp method, so that the mirror is rotated by the wind pressure in the travelling at more than a specific speed. Whereby the water drops attached to the mirror can be repelled with the sufficient centrifugal force.