Abstract: A method for producing a smooth finish on the surfaces of a valve seat and a discharge port of a fuel injection valve having a main fuel injection valve body containing an electromagnetic coil, a fixed core, a movable core attracted magnetically towards the fixed core by the coil and a valve rod attached to the movable core and having a valve body for opening and closing a fuel discharge port in a valve seat-forming member attached to the valve body. The fuel discharge port is formed with a smooth surface finish by discharging a honing fluid against the surface. The honing fluid is also discharged against the surface of the valve seat to provide a smooth finish thereon and to provide a rounded corner at the juncture of the seat surface and the fluid discharge port.