Since a notch 30 is formed in a circular arc form at a distal end upper corner portion of a protruding portion 16A, from a rear end portion of the protruding portion 16A towards a front side, even when a mirror 28 swings, a vehicularly transversely inward end portion 28A of the mirror 28 does not interfere with the distal end upper corner portion of the protruding portion 16A. Further, a front wall portion 16C of the protruding portion 16A is left at a front end portion of the notch 30. A front end portion 14A of a mirror body 14, the front end portion 14A facing the front wall portion 16C, is separated a predetermined amount from a side wall portion 30A of the notch 30 in an outward direction of a rotational radius. Accordingly, when the stay 16 is rotated a predetermined angle .theta. towards a front side of a vehicle body, a space S remains between the front end portion 14A of the mirror body 14 and the stay 16, and the front end portion 14A of the mirror body 14 does not interfere with the stay 16. As a result, since it is possible to bring the mirror 28 towards a side that is tranversely inward with respect to the vehicle, it is possible to dispose the mirror body 14 containing the mirror 28 towards the side that is transversely inward with respect to the vehicle.