To process a variety of infectious medical waste together and promptly.

A treatment method of infectious waste includes: a carbonization process for heat-treating the infectious waste by a heater while stirring and shifting by a stirring rotating means from a treatment tank on an upstream side in a thermal decomposition furnace A toward a treatment tank on a downstream side to carbonize by a thermal decomposition; a tar removal process for removing tar in an exhaust gas exhausted from an exhaust port of the thermal decomposition furnace by a tar removing apparatus B; a deodorization process for removing odor of the exhaust gas, from which the tar has been removed, by a deodorizing device C; and a de-smoking process for removing dust contained in the exhaust gas, from which the odor has been removed, by de-smoking apparatus D.