To adjust a car height by connecting a spring and an axle housing for rear wheels to each other through a joint member, and positioning a connecting point of the spring and the axle housing for rear wheels above or below a connecting point before the joint member is connected.

When a joint member is interposed between a transverse spring 4 and a spring connecting rod 12, since a connecting point Y of the transverse spring 4 to the spring connecting rod 12 after the joint member is installed can be positioned above or below a connecting point of the transverse spring 4 to the spring connecting rod 12 before the joint member is installed, a car height can be heightened or lowered by that extent. Since an originally provided leaf spring can be used, only the car height can be changed while setting elastic force of the spring in the same.