PROBLEM TO BE SOLVED: To provide an air purifying device capable of reliably performing disinfection using a sterilizing solution.SOLUTION: An air purifying device includes: a housing 50 having an air passage 52 through which air to be disinfected flows； a spray device 53 which sprays a bactericide solution into the air to be disinfected which flows through the air passage； a circulation reservoir 54 for receiving the bactericide solution falling from the air passage； a circulation system 55 for supplying to the spray device the bactericide solution of the circulation reservoir； a drug supply device 56 for supplying the bactericide solution to the circulation system； and a diluent system 571 for supplying a diluent for diluting the bactericide solution. In the purifier, the supply position where the stock solution of the bactericide solution supplied by the drug supply device in the circulation system is made to be different from the supply position where the diluent supplied by the diluent supply system, thereby forming an unused solution region having a high density at an inflow part of the circulation system where the stock solution of the bactericide solution flows in.
