PROBLEM TO BE SOLVED: To provide a method for dissolving a pyrethroid compound in water without causing separation or turbidity.SOLUTION: The method for dissolving a pyrethroid compound in water according to the present invention comprises incorporating, into an aqueous insecticide, a water-soluble polyoxyethylene hydrogenated castor oil and a non-water-soluble polyoxyethylene sorbitan fatty acid ester. Preferably, the water-soluble polyoxyethylene hydrogenated castor oil and the non-water-soluble polyoxyethylene sorbitan fatty acid ester are incorporated in a mass ratio of 90:10 to 30:70.SELECTED DRAWING: None