To provide an air cleaner, which eliminates pressure difference between an inner chamber and an outer chamber partitioned by an elastic body, can be used without deforming the elastic body, produces a good sound deadening effect, provides a stable sound deadening effect, and dispenses with a complicated work of installing the elastic body by applying a constant tension.

In the air cleaner, a cleaner case having an air intake port and a cover having an air discharge port are inter-joined, and an element is mounted to the internal space. A sound deadening chamber partitioned by a partitioning member containing at least an elastic material is formed in a dust chamber formed between the cleaner case and the element and/or between the cover and the element, and the partitioning member is provided with a communication part. The partitioning member made of the elastic material is disposed without loading tension.