PURPOSE: To provide an alignment adjusting mechanism with no large force required for alignment adjusting work by providing an adjusting means, by which an opening in a suspension arm opening side is adjusted, in a forked suspension arm of connecting a wheel supporting member vertically swivelably relative to a car body, so as to perform alignment adjusting.

CONSTITUTION: A closed side of a forked lower arm 24 is connected to a wheel supporting member, and an another end of an opened side of this lower arm 24 is connected to brackets in a car body side. A knuckle arm 23 is provided in a position of a vehicle displaced in its forward or rearward direction, in a knuckle 22, and a rod 26 of connecting the other end to a car body is connected to a point end of his knuckle arm. A tension rod 27 is inserted in the vicinity of an end part in the opened side of the lower arm 24, and an opening degree in the opened side of the lower arm 24 is adjusted by a nut 28 screwed to the tension rod 27.