An agrochemical oil-based suspension is a product commonly used among liquid agrochemical products, and if a resin-made agrochemical container is employed as a container in which the agrochemical oil-based suspension is to be filled, the container may be deformed or broken during storage or shipping.

With focus on use of a specific antioxidant, the present invention provides a method for preventing deformation of a resin-made agrochemical container by preparing a chemically stable agrochemical oil-based suspension having oxidation of an oil component in the suspension suppressed, and filling the suspension in the resin-made agrochemical container.