PURPOSE: To separate the synthetic resin layer from the base in the waste material of the synthetic resin made interior material by a method wherein the synthetic resin layer and the base are separated preliminarily to expose the joining part thereof and both of the synthetic resin layer and the base are pulled mutually under blowing high-pressure water against the joning part thereof.

CONSTITUTION: The waste material 1 of the synthetic resin made interior material is sent to a guide roller 3 by pinch rolls 2. The waste material 1 is separated preliminarily into the synthetic resin layer 1A and the base 1B at the guide roll 3 and the base is wound around a winding roll 4 through the guide roll 3. The high- pressure water is blown against the joining part of the synthetic resin layer 1A and the base 1B, which are separated by the preliminary separation, by a plunger pump 6 to separate them, thereafter, the synthetic resin layer and the substrate are retrieved respectively.