PURPOSE: To simply and rapidly evaluate a coating film decomposition degree when a regenerated material is produced by decomposing a coating film of a coated plastic waste.

CONSTITUTION: A coating film of a thermoplastic plastic waste coated with a thermosetting resin film is decomposed. This is melted and kneaded without removing the coating film to be produced as a regenerated material (sample resin) G. A fixed amount of the regenerated material G is put in a container 3 having a delivery hole 1 with a mesh 5 attached on the bottom thereof and melted. The melted regenerated material G is extruded from the delivery hole 1 through the mesh 5 by a plunger 4. While the extrusion load of the plunger 4 at this time is kept constant, a coating film decomposition degree is evaluated by an elapse time or a time change pattern until the discharge of the melted regenerated material G in the container 3 from the delivery hole 1. Alternatively, while the extrusion speed of the plunger 4 is kept constant, a coating film decomposition degree is evaluated by a load or a load change pattern of the plunger 4 during the discharge of the melted regenerated material G in the container 3 from the delivery hole 1.