To provide a leaf spring fitting structure capable of adapting to the change in the total thickness of a leaf spring only by changing the length of a U-bolt by providing a structure capable of changing the fitting angle of inclination of the U-bolt.

A center part of a leaf spring 1 is held and fixed by a nut 6 through an attachment 7 so that the center part is astride between a spring pad 2 provided on the upper face of the center part and a spring seat 4 by two tightening U-bolts 5. The respective sections of the U-bolt 5 and the spring pad 2 at the contact part are formed projected and recessed semi-circles having approximately same radius of curvature, and an U-bolt through hole 8 of the spring seat 4 is formed of long shape in the longitudinal direction of a vehicle, and the respective sections of the spring seat 4 and an attachment 7 at the contact part are formed projected and recessed semi-circles having approximately same radius of curvature. This constitution enables the change in the fitting angle of inclination of the U-bolt 5.