To reduce the product cost of CWM (Coal Water Mixture), CWM was produced using brown coal, that had been upgraded into oil. CWM ptoduced from the upgraded Roy-Yang coal pulverized by the conventional wet ball mill method had a low coal particle content of 49 wt%. To increase the coal content of CWM, the rounding method was applied, and the coal particle content of CWM was there by increased to 57 wt%. Based on these results, it may be concluded that the rounding method is effective for reducing the product cost of CWM.