Disclosed is a method which can readily design an agricultural chemical-containing resin composition having a desired release rate history and can produce the agricultural chemical-containing resin composition. Specifically disclosed is a method for producing an agricultural chemical-containing resin composition, including: respectively selecting an acetamiprid content Ac SA and a hydrophilic white carbon content Ca SA in the composition relative to the total mass of acetamiprid, a styrene-maleic anhydride copolymer or a styrene-maleic anhydride copolymer-mixed resin, and hydrophilic white carbon, so as to satisfy the inequations of: 0.524 x Ac SA +1.422 x Ca sSA - 6.009 ‰¤ 40% by mass, 5% by mass ‰¤ Ac SA ‰¤ 35% by mass, and Ca SA ‰¥ 0.1% by mass and mixing the acetamiprid, the styrene-maleic anhydride copolymer or the styrene-maleic anhydride copolymer-mixed resin, and the hydrophilic white carbon, so that the thus selected contents Ac SA and Ca SA can be achieved.
