PURPOSE: To give a change to a signboard to be seen through transmitted light and improve the workability at the time of manufacturing, by a method wherein a pattern is formed by providing unevenness having a thickness difference in a specific value on the surface of a sheet of thermoplastic resin.

CONSTITUTION: A pattern is formed on the surface of a transparent or semi- transparent colored sheet 1 comprised of thermoplastic resin such as flexible vinyl chloride by providing unevenness having a thickness difference of 2-10μm. In the manufacture of the sheet 1, and adhesive 4 is applied onto process paper 9 and dried, to which a colored sol 5 of transparent or semi-transparent thermoplastic resin scattered into a solvent is applied with a specified thickness. Then the subject method is performed by passing through a resin sheet to be formed by preheating the sol 5 between a base roll 8 into which the uneven pattern having a depth of 2-10μm is provided and a back-up roll 7 along with the process paper 9 on which an adhesive layer 4 is formed.