High Young's modulus steel containing TiB2 particles is known as one of the difficult-to-cut materials. For this reason, a tool life becomes very short in machining of this material. The purpose of this study is to investigate extension of the tool life in the turning of high Young's modulus steel. The optimum cutting speed and cutting edge shape were examined from the viewpoint of tool life and surface roughness. The results indicated a dramatic decrease in the tool life of K10-C tool due to scratching of the flank wear region by hard TiB2 particles. On the other hand, the cutting edge of a binder less cBN tool with a negative land angle was protected by the built-up edge, leading to a decrease in the cutting force and an extension of the tool life. For this tool, it was clarified that from the viewpoint of wear resistance and the machined surface, the optimum conditions were a cutting speed of 1.0 m/s and a negative land angle of 15 degrees. It was shown that the presence of a secondary chip allows these conditions to be achieved, and that a built-up edge leads to stability.