A filter assembly including: a first filter medium that is bent so that high-point portions and low-point portions defined based on a vertical plane with respect to a first direction are alternately and repeatedly formed in a second direction perpendicular to the first direction; a first filter frame configured to accommodate the first filter medium and to fix an edge side of the first filter medium; a second filter medium that is bent so that the low-point portions and the high-point portions based on the vertical plane with respect to the first direction are alternately and repeatedly formed in the second direction; and a second filter frame configured to accommodate the second filter medium and to fix an edge side of the second filter medium, wherein at least a portion of the high-point portions repeatedly formed in the first filter medium have different heights from those of the other high-point portions, and at least a portion of the low-point portions repeatedly formed in the second filter medium have different heights from those of the other low-point portions, and the first and second filter media are bent in such a way that a first filter medium high-point envelope connecting high points of the first filter medium and a second filter medium low-point envelope connecting low points of the second filter medium correspond to each other when viewed from a cross-section including the first direction and the second direction, and the first and second filter frames are combined with each other so that the first filter medium high-point envelope and the second filter medium low-point envelope face each other.