In the machining of metals, the chip formation influences largely on the cutting performance such as surface roughness of workpiece, cutting force, tool life and so on. The excellent chip formation requires a countermeasure for both tools and workpieces. When the tool is recognized, the rake face of tool where the chip is dominantly flown is very important. Especially in the case of ductile metals and alloys, the continuous chip appears and the rake angle increases. With this change, the cutting force decreases and, as a result, the cutting quality is improved. In addition, it is considered that the surface roughness of rake face may decrease because of the occurrence of more suitable chip flow. Simultaneously, the surface roughness of rake face becomes smoother so as to make the frictional force smaller. In this study, the effect of surface roughness of rake face on the cutting performance was experimentally examined. Cemented carbide tool (K10) is used as reference cutting tools. The cutting test was done repetitiously against aluminum workpiece (A5056). As a result, it is clarified that the surface roughness of rake face becomes intensively influential on the chip formation.