Mechanical properties of ultra-fine cemented carbides for precision molds are affected by VC and Cr3C2 which are added to as grain-growth inhibitors. Therefore, the addition effects of VC and Cr3C2 on ultra-fine WC-10%Co cemented carbides were investigated. It was confirmed that on the basis of hardness, the grain growth-inhibiting effect score of Cr3C2 is 0.38 with a score of 1 representing VC. We also confirmed the influence of Cr3C2 on the transverse rupture strength and the fracture toughness is smaller than that of VC.