The Co-Cr-Mo alloy is applied for dental casting alloy. This alloy though both mechanical properties, corrosion resistance are excellent, research and development in which in addition, the property is improved is advanced. In this study, mechanical properties and corrosion resistance were examined on the alloy which replaced Mo of Co-33Cr-5Mo-0.3N alloy in W. On The result showed that mechanical properties were improved, as the composition of W increases. And, though on the corrosion resistance, the improvement by addition of W was not observed, the lowering could not be observed either.