Bohler K-460 steel is a material commonly used in the field of cutting tool tools. The full hardening method is a method of heating the steel to austenite temperature by using a heating furnace (Heating furnace) that is done automatically. This method has several advantages including economical, easy to operate, applicative and time to heat the steel in stages and a short hardening. This research was conducted to investigate the effect of full hardening and media quenching on hardness in steel. This study uses Bohler K-460 steel which is subject to various treatments. the treatment that is applied to each specimen includes full hardening with a temperature of 4500C, 7500C, 9500C, and water, air, and oil quenching media. From the hardness test obtained the highest specimen hardness value in the specimen with full hardening treatment at a temperature of 9500C and oil quenching media. The highest hardness value is 2,023.2 HV. On microstructure observation, the above results are based on ASTM standards. From the SEM (Scanning Electron Microscope) analysis, the results showed that in the treatment of oil quenching media obtained carbon levels increased from 26.97% to 73.97%. It can be concluded that steel can be optimized using full hardening and quenching media so that it increases the hardness of steel significantly. Keyword : Full Hardening, Quenching Media, Hardness