Generally, the laser flash method is only used to measure thermal conduction in the cross-plane direction. This study measured the thermal diffusivity of isotropic graphite (IG 110) in the cross-plane and in-plane directions. The cross-plane (or through-plane) direction is perpendicular to the substrate plane, and in-plane (or radial plane) direction is parallel to the substrate plane. In the laser flash method, thermal diffusivity shows a decreasing tendency as laser energy increases. Thermal diffusivity was taken as intrinsic thermal diffusivity for all specimens, as this method eliminates the influence of the laser's energy level as a factor. The cross-plane and in-plane thermal diffusivity of IG IG-110 were 10.13 x 10(-5) m(2)/s and 9.88 x 10(-5) m(2)/s, respectively.