PURPOSE: To improve catching efficiency and safety, by forming the electrode of an air purifier with a slanted dust collecting board, and taking out minus high voltage by a high voltage block and applying to a discharge electrode.

CONSTITUTION: A charging section 5 is formed by a discharge electrode 1. Particles 4 pulled by air current of a fan etc. are charged in the charging section 5 and attracted by a dust collecting section 6 and collected. In this case, catching point is shown by B as the dust collecting electrode 6 is inclined to make catching time quicker by time (t). On the other hand, a high voltage block reverses a high voltage commutator 10, takes out minus high voltage and applies this to the discharge electrode 1. As the discharge electrode 1 emits a large quantity of minus ions, very fine particles and odorous particles act effectively. High resistance 12 is provided to prevent destruction of the high voltage block due to short-circuiting etc.