AIR CLEANER

PROBLEM TO BE SOLVED: To provide an air cleaner which is made more compact or has reduced pressure loss.SOLUTION: A positive electrode 110, a negative electrode 120, a photocatalyst module 130, and an ozone decomposition catalyst module 140 are provided inside a casing 150. At least one of the positive electrode and the negative electrode, the photocatalyst module and the ozone decomposition catalyst module are arranged in the order from the upstream side of the flowing direction of a body to be treated, and a substance to be decomposed, that is provided in the body to be treated, is decomposed on the basis of the action of a photocatalyst activated by the light of discharge generated by applying a voltage between the positive electrode and the negative electrode and reaction with an oxygen radical generated when ozone generated during the discharge is reduced by an ozone decomposition catalyst.