Abstract: The method for exterminating plants pests comprises making an adjustment for causing the aqueous solution for exterminating pests to have the concentration within the range between the upper limit of being, by 0.4 mol/l, higher than the concentration of the said cell sap of plants and the lower limit of 0 concentration, and dipping the said plants in the said aqueous solution adjusted at the above concentration for a period of time required for exterminating pests.When the concentration of the said aqueous solution is adjusted within the ranged mentioned above, the pests gathering on the said plants may be suffocated to death without doing any harm to the plants dipped in the said aqueous solution.