Abstract: The present invention relates to a method for preparing an optical sheet comprising the steps of: (a) preparing a transfer film having a single roughened side by coating one side of a first substrate with resin component comprising 100 parts by weight of binder resin and 70 to 130 parts by weight of spherical organic polymer beads, followed by drying; (b) laminating the transfer film preparing in step (a) with an ultraviolet-curable (UV-curable) resin-coated layer, which prepared by coating one side of a second substrate with UV-curable resin, such that the roughened side of the transfer film is facing the UV-curable resin-coated side of the second substrate; and (c) forming a roughened diffusive layer on the single-side of the second substrate having refractive index of 1.41 to 1.59 by curing the laminate obtained in step (b), followed by separating and removing the transfer film, wherein the roughened side of the transfer film has a segment angle of 130 to 150°.