High grade limestone was obtained by removing trace impurities through reverse and carrier flotation techniques. A simple method for measuring the impurity content of limestone was developed by correlating the amount of impurities and the turbidity of suspensions of residue from limestone dissolved in 20% acetic acid.Impurity removal more than 50% with limestone recovery better than 85% was obtained under suitable conditions by both reverse flotation and carrier flotation using sodium oleate (NaOl) and dodecylammonium acetate (DAA) as collectors. Limestone containing more than 0.15 mass% impurity was used as the carrier. These results suggest that limestone treated by flotation can be used as high quality limestone in paper manufacturing.