PURPOSE: To provide an air filter where a filter member is cleaned with a device, such as a computer remaining in the operating condition in the air filter installed in a forced air-cooled part of the computer, etc.

CONSTITUTION: An air filter is constituted of a pair of rollers 2, 3 arranged parallel and opposite to each other in an equipment frame 80, a filter member 1 in the shape of an endless belt movably held by a pair of the rollers 2, 3, a cleaning brush 5 arranged with its end part coming into contact with the filter member 1, a dirt container 10 which a pan part 8 for receiving the dirt a blown off by the cleaning brush 5 is provided to form and a roller drive means 15 for imparting rotational force to a pair of the rollers 2, 3.