The present invention provides a graphite sheet having a ratio of thermal diffusivity in horizontal and vertical directions of 300 or more. Also, the present invention provides a graphite sheet having a ratio of thermal diffusivity in a vertical direction of 2.0 mm2/s or less. The graphite sheet has excellent thermal conductivity in horizontal and vertical directions and excellent flexibility at the same time and can be produced at low manufacturing cost, thereby holding an economic advantage.