PROBLEM TO BE SOLVED: To remarkably improve purification treatment efficiency by a plasma discharge and photocatalysis even when driving by use of a low-voltage small-capacity power source such as a dry battery.SOLUTION: This air cleaner is disposed with plasma excitation photocatalyst units (2) decomposing pollutant in the air by a normal temperature atmospheric pressure plasma discharge and decomposing the pollutant by a photocatalyst excited by ultraviolet light generated according to the plasma discharge, inside air flow passage. In the plasma excitation photocatalyst unit (2), a cylindrical porus photocatalyst element (7) is installed to an installation hole (9) formed in a flat plane electrode (8), an inner space of the photocatalyst element (7) is formed as a purification treatment space (6) through which air flows, and an acicular electrode (13) generating the plasma discharge with the flat plate electrode 8 is provided in the purification treatment space (6) such that the acicular electrode (13) projects into the purification treatment space (6) from one opening part (4) of the porus photocatalyst element (7).
