PURPOSE: To provide an air filter which is light in weight, and produced at a low cost by a method wherein a frame member having a filter member installed therein is comprised of a frame for enclosing side edges of the filter member, a filter supporting member for supporting one end surface of the filter member, and a filter-fitting part having a U-shaped section formed at a side of the filter member of the frame.

CONSTITUTION: A filter 17 has a frame member 19. The frame member 19 is comprised of a frame part 24 enclosing side edges of a filter member 31; a filter supporting member 21 for supporting one end surface of the filter member 31; and a filter fitting part 25 having a U-shaped section formed at the frame part 24, wherein a supporting surface of the filter supporting member 21 is provided with a large opening 23. In turn, a main body of an air conditioner is provided with a fitting part to which the frame member 19 having the filter member 31 installed therein is fitted. When fitted, the filter fitting part 25 performs a function acting as a rail to be fitted to the fitting part of the main body of the air conditioner. The filter member 31 is constructed such that a deodoring filter and an electrical charging filter having an electrical load charged therein are overlapped to each other.