A composite sintered material includes: a plurality of diamond grains having an average grain size of less than or equal to 10 μm; a plurality of cubic boron nitride grains having an average grain size of less than or equal to 2 μm; and a remainder of a binder phase, wherein at least parts of adjacent diamond grains are bound to one another, the binder phase includes cobalt, in the composite sintered material, a content of the diamond grains is more than or equal to 30 volume % and less than or equal to 94 volume %, a content of the cubic boron nitride grains is more than or equal to 3 volume % and less than or equal to 40 volume %, and a content of the cobalt is more than or equal to 3 volume % and less than or equal to 30 volume %.