. O In a vehicle having an interior room mirror and a pair of exterior right and left side mirrors, a single photo sensor is provided for detecting an intensity of light incident from the rear of the vehicle. A driving circuit drives both the room mirror and the side mirrors into a dazzle-free condition in common when the photo diode detects the intensive rear light. Alternatively two photo sensors are provided for detecting not only the intensity of the rear light but also direction of the rear light and both the room mirror and one of the right and left side mirrors are driven into the dazzle-free condition in accordance with both the intensity and direction of the rear light.