Air-conditioning air filter

An air-conditioning air filter comprising:

• a main box made of plastic and having a shape in which an air inlet is opened in a front side and an air outlet is opened in a back side, an upper side is closed by a top plate, a bottom side is closed by a bottom plate, and right and left sides are closed by right and left side plates, respectively;
• and a plurality of filter bodies which are extractably accommodated in a zigzag manner between said air inlet and said air outlet in said main box, each of said filter bodies being formed by fitting a filter element in the shape of a bellows into a rectangular filter frame, wherein sliding channels are formed in upper end faces and lower end faces of said filter frames, respectively, over a whole length in anteroposterior direction, right and left guard rails having a shape which covers both sides of said upper end faces and said lower end faces of said filter frames, and guide rails which being placed in parallel with and between said right and left guard rails and to be slidably fitted with said sliding channels are protrudingly formed in a zigzag manner on inner faces of said top plate and said bottom plate of said main box, respectively, engaging projections being protrudingly and horizontally disposed on inner sides of said right and left guard rails, and engaging channels which are to be slidably engaged with the engaging projections being formed over a whole length in anteroposterior direction on both side faces of said upper end portion and said lower end portion of each of said filter frames, wherein said guide rails are formed into a convex section shape, and said sliding channels are formed into a convex section shape corresponding to the convex section shape of said guide rails.