A sterilizing apparatus installed on a car includes a nozzle-installing pipe on which a plurality of nozzles are mounted at regular intervals, a driving mechanism for varying the spray angles of the nozzles, a driving mechanism for controlling the spray time periods, a supply mechanism for supplying disinfectant to a disinfectant-flowing path equipped in the nozzle-installing pipe, a plurality of tanks containing disinfectant to be supplied to the supply mechanisms and control mechanisms for controlling the operation of the driving mechanisms. The car is moved to a required place in a hospital, and the nozzles are operated by spray disinfectant particles, the diameter of which are 10 .mu.m or less.