Abstract: An electronic air cleaner, in which an air inlet, a mechanical prefilter, an electrifying cell, an electrostatic collector cell, a chemical filter and an air outlet are arranged in the order in a casing of insulating material. The electrifying cell comprises a grounded conductive protection net located behind the mechanical prefilter, a plurality of thin-wire electrodes and a plurality of grounded conductive plates. The thin-wire electrodes are less than 50 microns in diameter and arranged in appropriate intervals at substantial rectangles with an air path from the air inlet to the air outlet. Each of the grounded conductive plates has one end attached to the protection net and backwardly extending between adjacent two of the thin-wire electrodes along the air path.