PURPOSE: To obtain a captioned steel plate prevented surely from rusting by a method wherein a cutting edge face produced by cutting a synthetic resin coated steel plate in a proper length is coated with a synthetic resin film again in a mold.

CONSTITUTION: A synthetic resin coated steel plate 3 obtained by coating a whole surface of the steel plate 1 with the synthetic resin 2 is cut in a proper length. Subsequently, a cutting edge face portion 4 of the cut coated steel plate 6 is pushed into a recessed portion of a mold and synthetic resin is injected into the recessed portion to obtain a totally resin coated steel plate, the cutting edge face portion 4 of which is coated with synthetic resin 7. A film thereof is stronger compared with the same obtained by painting the synthetic resin onto the cutting edge face portion 4 only, and generation of rust may be prevented surely.