PROBLEM TO BE SOLVED: To prevent risks such as explosion and combustion due to invasion of air at the time of pyrolysis of infectious medical waste and the like, to simultaneously perform destruction and sterilization of a storage container of medical waste, and to prevent a pyrolysis gas from being discharged into the atmosphere until reaching a sterilization temperature set by the government.SOLUTION: A sterilizing device, where two feeders are combined to discharge air, each feeder is narrowed at its tip, and the tip provided with a blade is placed in a sterilization chamber, is provided with a vertically movable cutting blade, a breaking blade of a rotary breaking machine, two dampers which move alternately between the sterilization chamber and a pyrolysis tank, and a damper which is disposed at a pyrolysis gas outlet and through which superheated steam is ejected.【課題】感染症医療廃棄物などを熱分解時に空気の侵入による爆発、燃焼等の危険を防止し、医療廃棄物の収納容器を破壊と同時に殺菌し、国の定める殺菌温度に達するまで熱分解ガスを大気放出させないことは可能か。【解決手段】供給装置を2基組み合せ抜気して、供給装置先端を絞り、刃物を設けたその先端を殺菌室内に置き、上下可動の切断刃と回転破壊機の破壊刃と殺菌室と熱分解槽間に交互に動く2基のダンパーと殺菌室内に過熱蒸気を噴出し熱分解ガス出口にダンパーを設ける。【選択図】図1