In this report the method for pure culture of protozoa found in bovine rumen is discussed, and the best method for isolating and culturing the protozoa is here stated. The airdried contents of bovine rumen are treated with 30% HCl solution for 40 minutes or 10 or 20% HCl solution for 24 hours, and put in the culture solution which is compound from Ringer's solution (8 parts) and bovine serum (1part). When cultured at 37℃ for 24 hours. Entodinia are observed in all cases and the bacteria were not found to be alive in the case of the treatment with 10, 20 and 30% HCl solution. Other protozoa e.g. Dastrica, Diprodinium, Isoirica, have been found when the rumen contents are neutrized by caustic, soda after treated with HCl solution.