PURPOSE: To prevent deterioration in performance by providing the filter furnished with a conductive metallic plate in a part of a filter main body and providing an air cleaner main body.

CONSTITUTION: An arithmetic circuit 6 is put into operation in response to the output of a detecting circuit 5. The arithmetic circuit 6 receives the signal sent from an operation part 8 only when the detecting circuit 5 detects the short-circuit between electrodes A and B, and, in another case, the air cleaner is inhibited to be put in operation. The arithmetic circuit 6 carries out addition and stores it in every specified period when the electrodes A and B are in short-circuit and the air cleaner is in operation, and a signal is outputted to an information circuit 7 when the sum total exceeds specified value to inform the time to exchange the filter 1. By this method, the operability is improved and the time to exchange the filter is correctly informed.