A method of eradicating pathogens and pests and a device for eradicating pathogens and pests are provided that can efficiently generate an OH radical and that are excellent in the effect of eradicating pathogens and pests.Water such as water mist is introduced into a reaction container (2), a plasma-forming gas is supplied from a gas supply portion (3) to a reaction container (2), voltage is applied between a negative electrode (5) and a positive electrode (6) provided in the reaction container (2) to discharge the gas and generate an OH radical, the OH radical is applied to an item to be sterilized or a pest to be killed and thus they are eradicated. The gas is any one of air, helium and argon or a mixture of these gases. The amount of OH radical generated may be controlled by controlling the amount of water mist supplied or the amount of gas supplied.
