To easily conduct periodical maintenance such as the cleaning of an air filter at the suction port of an indoor apparatus of an air conditioner and to provide functions such as an air cleaning effect and a comfortable space in a room.

The air filter 1 made of nonwoven fabric or filter paper is attached to the suction port 6 of an indoor apparatus 5 for an air conditioner 5 through mounters 3 provided at the upper part, left and right of the rear of the filter 1. The air filter 1 forms a multilayer structure with the internal filter of the apparatus 5, the suspended matter in a room is mostly collected with the filter 1, and the filter is easily cleaned and replaced. Consequently, the contamination of the filter in the apparatus 5 is reduced, and the filter is used for a long period. Further, a deodorizing or antibacterial material 4 is laminated on the filter 1 to promote the air cleaning function, and a comfortable space is obtained in the room along with the pattern and landscape 2 drawn on the filter 1 surface.