A high thermal conductive silicon nitride sintered body having a thermal conductivity of 50 W/m·K or more and a three-point bending strength of 600 MPa or more, wherein when an arbitrary cross section of the silicon nitride sintered body is subjected to XRD analysis and highest peak intensities detected at diffraction angles of 29.3±0.2°, 29.7±0.2°, 27.0±0.2°, and 36.1±0.2° are expressed as I29.3°, I29.7°, I27.0°, and I36.1°,
- a peak ratio (I29.3°)/(I27.0°+I36.1°) satisfies a range of 0.01 to 0.08, and a peak ratio (I29.7°)/(I27.0°+I36.1°) satisfies a range of 0.02 to 0.16.