A method of manufacturing the optical sheet is provided. The method includes: a first step of heating a composition containing a liquid crystal monomer or liquid crystal prepolymer and a photopolymerization initiator at a temperature equal to or higher than a melting point of the liquid crystal monomer or liquid crystal prepolymer and pressing the composition in a state where the composition is held between a master including a plurality of solid structures disposed continuously in one surface and having shape anisotropy in the one surface and a light transmission film disposed so as to face the solid structures of the master. The method also includes a second step of irradiating the composition with ultraviolet rays at a temperature lower than a phase transmission temperature to an isotropic phase to polymerize the liquid crystal monomer or liquid crystal prepolymer and, after that, separating the light transmission film from the master.