A manufacturing method of deformed steel bars by cold rolling and cold drawing is provided to improve productivity substantially by completing a cold drawing process for a shorter time compared to a conventional manufacturing method, thereby further reducing the working hour, and lower product cost and improve product competitiveness by mass-producing the deformed steel bars. A manufacturing method of a deformed steel bar by cold rolling and cold drawing comprises: a steel material inspecting and preparing process(N1) of inspecting a material and a surface state of a steel material and preparing the steel material having a length corresponding to that of a final product; a heat treatment process(N2) of heating the steel material to soften structure of the steel material by lowering hardness and tensile strength of the steel material; a peeling process(N3) of cutting a surface of the heat-treated steel material; a cold rolling process(N4) of feeding the peeled steel material into a horizontal or vertical rolling mill using a loading table, and cold rolling the steel material; an intermediate heat treatment process(N5) of heating the hardened steel material after cold rolling to soften the steel material; a coating process(N6) of removing scales, which are formed on the surface of the intermediate heat-treated steel material, by shot-blasting, and coating a coating solution on the surface of the steel material; a cold drawing process(N7) of loading the coated steel material on a draw bench and drawing the steel material; and an inspecting and correcting process(N8) of inspecting and correcting a drawn product.
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