We have attempted to improve performance of cutting tools by coating on tool edge surface with a hard and lubricious thin film. In this work, B-C coatings have been prepared on silicon and tungsten carbide substrates by DC magnetron sputtering with a sintered B₄C target. For obtaining excellent frictional properties in the B-C coatings, CH₄ gas was introduced as a plasma gas Nano-indentation studies showed that the CH₄ introduction in the film formation process led to a lower hardness of the film. On the other hand, the adhesive strength to the substrate was increased by the CH₄ introduction in the film formation process. Furthermore, the frictional properties of the B-C coating against a steel ball in an ambient atmosphere were improved by CH₄ addition and their friction coefficients reduced from 1.0 to 0.4. Then, we created B-C coated tools, and evaluated the cutting performance against a stainless steel by using a high speed precision lathe. The B-C coated tool showed better cutting performance than non coated tool. However, the B-C coating was peeled off from the tool edge at the cutting length of 1000 m in a dry condition.