PURPOSE: To automatically separate only one article by thermally welding the articles consisting of materials which are different in m.p.

CONSTITUTION: The articles consisting of the materials which are different in the m.p., for example, empty container group 6 in which prerolled metallic containers 7 and plastic containers 8 coexist are passed in the spacing between a flat belt 1 and a welding heat drum 2 while the groups are carried by the flat belt 1. The metallic containers 7 past this spacing are housed into a metals housing box 5. On the other hand, the plastic containers 8 are fused by the heat of the welding heat drum 2 and are stuck to the surface of the drum 2. The drum 2 is then rotated and when th rolled plastic containers 8 sticking to the drum come to the position where a detaching tooth 3 is disposed, the containers are detached from the surface of the drum 2 by the plastic tooth 3, by which said containers are housed into a plastic housing box 4.