There is a glaring need for omitting intermediate heat treatments in the manufacturing processes of carburized parts and increasing the carburizing temperature aimed at cost reduction. It is necessary to develop techniques to inhibit grain-coarsening since some austenite grains tend to grow abnormally during carburizing and coarse grains have negative effects on the properties of parts. Therefore, we developed new techniques to inhibit grain-coarsening by refining precipitates’ size and increasing their volume fraction based on the abnormal grain growth theory by Gladman. In this study, AlN and Nb(CN) were chosen as the precipitate particles for the pinning of austenite grain growth. And we investigated grain-coarsening behavior in several manufacturing processes of parts. As a result, we developed anti-coarsening steels for various manufacturing processes of carburized parts.