Substitutions from high alloyed steels to B-added steels are increased rapidly, because the prices of alloying elements are increased. To increase the maximum hardness of B-added steel, 0.5% C containing B-added high carbon steel developed. One of the old problems to manufacturing high carbon steel is control of cooling in Run-Out-Table (ROT) in hot rolling mill. Especially, the shape problems of coil such as collapsed coil or twisted coil are frequent in the B-added high carbon steels because of their relatively higher hardenability than plain high carbon steel and relatively lower strength than high alloyed steels in high temperature. In order to solve this problem in 0.5% C containing B-added steel, a new ROT cooling model is suggested and tested. The basic concept of this new cooling model is using the medium temperature pyrometer and feed-back control mechanism. The shapes of coils tested 0.5%C containing B-added steel are very good without collapse or twist. One of test manufactured coil is cold rolled and annealed in cold rolling mill to make test specimen for automatic transmission parts. The manufacturability in cold rolling mill is also better than that of high alloyed steel. The cold rolled test specimens are formed to test automotive transmission parts and heat treated. The test parts made by 0.5% C containing B-added high carbon steel developed shows same or higher durability than the old one.