A belt connecting metal fitting for a seat belt device of a vehicle comprises a metal fitting plate body, and a belt insertion means formed as a slot formed to the metal fitting plate body through which a seat belt is inserted. The belt inserting slot is provided with bulged portions on both surfaces of the plate body so as to provide a thickened portion at least to an edge portion with which the belt is engaged to form a central belt insertion hole, the edge portion of the belt inserting slot having substantially circular curved cross section. A belt mounting hole is formed to the metal fitting plate body to secure the belt. At least the belt engaging portion of the metal fitting plate body is coated with a resin material formed through a resin molding process with the belt insertion hole remaining uncoated.