A method of manufacturing a diffusion sheet is provided to diffuse the light through a diffusion pattern having an uneven shape formed on a surface of the diffusion sheet without using a diffusing agent, thereby reducing manufacturing cost. A method of manufacturing a diffusion sheet(300) comprises the following steps of: forming a relief pattern on a side of a base substrate; forming an imprint mold(200) including an intaglio pattern(210) corresponding to the relief pattern; and compressing the imprint mold to the base sheet and forming the diffusion sheet having a diffusion pattern(322) corresponding to the intaglio pattern. The step of forming the imprint mold comprises the following steps of: spreading a mold material on a side of the base substrate; and separating the spread mold material from the base substrate.
