Cubic boron nitride sintered body and cubic boron nitride sintered body tool

A cubic boron nitride sintered body comprising cubic boron nitride and a binder phase, wherein

• a content of the cubic boron nitride is 82 volume % or more and 98 volume % or less,
• in a cross section of the cubic boron nitride sintered body, an isolated binder phase having an area of 0.05 μm2 or more and 0.5 μm2 or less has a protrusion of two or more steps with respect to the cubic boron nitride, and
• assuming that in a first-step protrusion from a tip of the protrusion, A1 represents a side length which is perpendicular in a tip direction, and B1 represents a side length which is parallel in the tip direction;
• and in a second-step protrusion from the tip, A2 represents a side length which is perpendicular in the tip direction, and B2 represents a side length which is parallel in the tip direction, an area ratio of an isolated binder phase having a protrusion in which A1/B1 is one time or more and ten times or less of A2/B2, to the whole of the isolated binder phase having the area of 0.05 μm2 or more and 0.5 μm2 or less, is 25% or more.