The present disclosure sucks air in hospital room using a compressor to maintain an inner portion of the hospital room in a negative pressure state, and creates a high-temperature and humid environment by a water spray, the compressor, and a sterilization chamber to kill bacteria or viruses. In addition, the compressor uses power generated by a turbine, and is configured so that heat of air coming out of the compressor is recovered to a suction side of the compressor, such that efficiency of a system may be secured. Further, some of clean air generated while passing through the sterilization chamber may be directly supplied again to the hospital room through a bypass means.