An object of the present invention is to provide a cubic boron nitride sintered body and a coated cubic boron nitride sintered body that can extend the tool life by having excellent wear resistance and fracture resistance. A cubic boron nitride sintered body including cubic boron nitride and a binder phase, wherein in a cross-sectional structure, content ratios of the cubic boron nitride and the binder phase fall within specific ranges, the binder phase includes a Ti compound phase containing a specific compound, an Al compound phase containing a specific compound, and a W compound phase containing WC, an average grain size of the W compound phase is 0.5 m or more and 3.0 m or less, content ratios of the Ti compound phase and the Al compound phase based on a whole of the binder phase fall within specific ranges, a content ratio X1 of the W compound phase is 2.0 area % or more and 30.0 area % or less, a content ratio X2 of the W compound phase based on a whole of the binder phase in a range from an interface between the cubic boron nitride and the binder phase to a distance of 300 nm toward the binder phase side is larger than the content ratio X1.