To provide an air cleaner allowing a catalyst to be continuously serviced in an activated temperature state in the air cleaner using the catalyst.

In this air cleaner 10, a porous filter 2 carrying the catalyst, a heater 3 heating air passing through the porous filter, and a counter flow type heat exchange part 4 are stored in a bottomed vacuum insulated container 1. The filter 2 can be activated when heated by the heater 3, non-cleaned air 8a is heated by the heat exchange part 4 and supplied to the filter 2 for cleaning. The cleaned air 8b is cooled by the non-cleaned air 8a and blown in a state near that in the room temperature.