To provide an electrification filtering medium capable of exhibiting a high particle capturing efficiency relative to fine dust at a low pressure loss by a combination of polyester based fiber and polyolefin based fiber and having an anti-bacterial property and an anti-allergenic property itself and to further provide an electrification filtering medium in which an inflammability division according to "firing test method of organic material for automobile cabin of JIS D 1201 (1977)" is self-extinguishing and dioxins are not generated at incineration disposal.

The frictional electrification filtering medium is produced by subjecting a fiber aggregate containing at least 20 mass% of the polyester based fiber having a phosphinic acid compound in a side chain and at least 30 mass% of the polyolefin based fiber to an alkali treatment and subjecting to a frictional electrification treatment.