To provide a treating device for plastic-metal composite material which can save fuel and significantly reduce the quantity of a waste.

This treating device thermally decomposes the plastic or rubber of a waste plastic- or rubber-metal composite material by heating the waste in dry distillation furnaces 1A and 1B maintained in superheated steam atmospheres, and recovers an unoxidized metal. The dry distillation furnaces 1A and 1B are successively switched to each other for operation and the holding heat of the waste gases from the furnaces 1A and 1B are utilized for preheating the next operated furnaces 1B and 1A.