PURPOSE: To abandon without any public harm a disposal tatamimat including a plastic part by rendering the disposal tatamimat to cutting, heating with hot air, and burning and cleaning decomposed gas, separating and recovering light oil, and carbonizing and recovering a plant fiber part.

CONSTITUTION: A disposal tatamimat 1 cut with a cutter 2 is introduced into a rotary kiln 3, and a plastic part of cut pieces of the tatamimat 1 and the like introduced into the rotary kiln 3 is thermally decomposed into light oil and decomposed gas and plant fibers involved in the cut pieces are carbonized in a hot air producing furnace 8. The decomposed gas is introduced into a gas burning furnace 28 and is guided into a gas cleaner 29 after the burning. Further, the light oil is recovered by light oil discharge sections 12 located at the center and end of the rotary kiln 3. Carbides of the plant fibers are ground in a screen chamber 19 located at the other end of the rotary kiln 3 and are dropped through gaps of the chamber for recovery thereof. Thus, a plastic tatamimat is abondoned without any public harm.