Abstract: A cBN sintered body excellent in chipping resistance and wear resistance in working difficult-to-machine centrifugally cast iron is provided. The present invention is directed to a cBN sintered body composed of a cBN component not lower than 50 volume % and not higher than 90 volume % or not lower than 40 volume % and not higher than 85 volume %, characterized in that the cBN sintered body contains alumina and zirconia not lower than 9 volume % and not higher than 50 volume % and a weight ratio of zirconia/alumina is not lower than 0.1 and not higher than 4. A tool including the cBN sintered body according to the present invention in a portion involved with cutting achieves improved performance in working difficult-to-machine centrifugally cast iron as compared with a conventional tool made of a cBN sintered body, because the cBN sintered body is excellent in strength, hardness and toughness.