To provide a method for sterilizing/volume-reducing waste and valuables as much as possible, especially medical waste, safely in consideration of environment, and an apparatus for the method.

An apparatus 10 for carbonizing waste comprises a treatment chamber 12 which houses waste and is closed by a partition wall 24 which can make the chamber 12 be shut off from outside air, a heating chamber 16 which covers a part including the lower part of the chamber 12 or the whole chamber 12 and has a heater 14 for heating the chamber 12, and a generated gas supply apparatus 18 which is heated by a heater 14 and leads gas generated by the pyrolysis of the waste in the chamber 12 to the heater 14.