Citrus unshiu farming has been assumed to be hard to develop on large-scale farms because of its labor intensive technical character, which makes mid-sized farms is superior to large farms. However large-size citrus farms are developing in Mikkabi, Shizuoka Prefecture, where improvement of production infrastructure is most advanced and market competitiveness in citrus unshiu has been strong. Therefore the technical systems in Mikkabi which have supported development of large-scale citrus unshiu farming were analyzed by a farm survey. Though mid-sized farms, which are within the existing appropriate farm size, are superior to large farms in land productivity, large farms, which for the most part exceed the existing appropriate size, are superior to mid-sized farms in labor productivity. The large farms have achieved high productivity by the introduction of technology which makes best use of improved production infrastructure such as mechanization and mulching cultivation, adoption of quality improvement technology such as mulching cultivation, and input of a large amount of hired labor.