Abstract: A cBN sintered compact comprising a cubic boron nitride and a ceramic binder phase, wherein a cubic C-containing Ta compound in an amount of 1.0 to 15.0 vol % is dispersed in the ceramic binder phase and has a mean particle diameter of 50 to 500 nm.

Abstract: A cBN-based ultra-high pressure sintered body contains cBN particles and a binder phase. The binder phase contains at least one of a nitride or oxide of Al or a nitride, carbide, or carbonitride of Ti, and a metal boride having an average particle diameter of 20 to 300 nm is dispersed in an amount of 0.1 to 5.0 vol % in the binder phase. The metal boride includes a metal boride (B) containing at least one of Nb, Ta, Cr, Mo, and W as a metal component and containing no Ti and a metal boride (A) containing only Ti as a metal component. In a case where a ratio (vol %) of the metal boride (A) in the metal boride is represented by Va and a ratio (vol %) of the metal boride (B) is represented by Vb, a ratio of Vb/Va is 0.1 to 1.0.