Abstract: The challenge of the present invention is to provide a multilayer filter medium whose deodorizing performance after a long-term storage of the filter medium is suppressed from deteriorating and which is superior in deodorizing performance and exhibits low pressure drop. A multilayer filter medium includes three or more nonwoven fabric layers superposed together and has two or more interlayer regions each formed by two adjacent layers of the nonwoven fabric layers, in which a first interlayer region of the interlayer regions contains functional particles A having an average particle diameter of 50 to 100 ?m, and a second interlayer region selected from the interlayer regions excluding the first interlayer region contains functional particles B having an average particle diameter of 150 to 500 ?m.