PURPOSE: To enable a jet honing device to be lessened in production man-hours and production term and enhanced in productivity by a method wherein a jet honing device used for removing dam resin is combined with a water brush unit into a device of integral structure.

CONSTITUTION: A jet honing device is equipped with a lead frame feed section 11 which feeds resin-sealed lead frames 2 one by one, a lead frame positioning- fixing section 8 which positions and fixes a lead frame 2, and a nozzle head 5 which jets water of high pressure against the lead frame 2 with a jet nozzle 4 to remove dam resin. A water brush unit section 19 is provided to spout out water of high pressure from a linear nozzle 15 fixed to a movable stage 17 against both the rear and front of the lead frame 2 where dam resin has been removed off to remove resin burrs and smuts from the lead frame 2. Furthermore, a lead frame housing section 12 where the lead frame 2 passing through the water brush unit section 19 is housed in a magazine 10 and a lead frame transfer section 9 are provided.