To provide an ion generation method which enables the stable discharge of high density negative ions by high reduction potential or high density positive ions by high oxidation potential to enable the cleaning of polluted air or the treatment of sewage due to a reduced amount of a chemical agent.

A high frequency AC of 1-100 kHz is inputted to the primary sides of a paired set of high frequency output transformers and output voltage of 3,000-30,000 V is applied to the secondary sides thereof. Negative high voltage AC pulses with a pulse frequency of 0.5-50 kilopulses/sec being negative high voltage are outputted from one high frequency output transformer and positive high voltage AC pulses having the same pulse frequency are outputted from the other high frequency output transformer. One of a pair of switching converter converts positive high voltage DC pulses intermittently in a ratio of 1/20-1/100 with respect to the negative high voltage DC pulses to be mixed therewith and the other one of them converts negative high voltage DC pulses in a ratio of 1/20-1/100 with respect to the positive high voltage DC pulses to be mixed therewith to apply negative and positive DC pulses to a discharge electrode.