The object of the present invention is to provide a method of producing a fruit of a Capsicum plant in which a vitamin C content, in particular a vitamin C content alone and is increased according to a common cultivating procedure without requiring special facility and cultivating procedure. The present invention provides a method of producing a fruit of a Capsicum plant with an increased vitamin C content and characterized by inoculating an attenuated strain of a virus belonging to Tomamovirus to a seedling of the Capsicum plant and cultivating the seedling to the Capsicum plant.