A manufacture method of an optical sheet made of a transparent thermoplastic resin sheet on whose surface a regular geometric design working is performed, the optical sheet manufacture method comprising steps of performing a geometric design working on the resin sheet at a temperature not lower than a glass transition temperature of the resin sheet, by using a metal endless working belt formed with a geometric design on a surface thereof, rapidly cooling the resin sheet on which the geometric design working is performed to a temperature lower than the glass transition temperature, and detaching the rapidly cooled resin sheet from the metal endless working belt.