A composition including active ingredients of penthiopyrad and at least one neonicotinoid compound chosen from the group consisting of dinotefuran, clothianidin, nitenpyram, thiamethoxam, imidacloprid, thiacloprid, and acetamiprid, and a plant disease and insect damage prevention method of applying such a composition to a plant seed, are provided. According to the invention, a composition and a prevention method are provided which demonstrate a high degree of prevention effect and residual effectiveness against plural types of disease and insect damage, and also demonstrate a stable preventing effect to currently emerging resistant pathogens and resistant pest insects.
