When a characterization of a tip of a diamond stylus for working is needed, the tip of the diamond stylus for working used is observed by a high resolution scanning electron microscope of a high acceleration voltage under a steam atmosphere. When the tip of the diamond stylus for working is worn or when a shape of the tip of the stylus needs to be changed, the tip of the diamond stylus for working is worked by selectively irradiating an electron beam only to a necessary region by increasing an amount of steam and an amount of a current of the electron beam. When a working chip is strongly adhered to the diamond stylus for working and needs to be removed, the electron beam is selectively irradiated only to the working chip adhered to the tip of the diamond stylus for working to be removed under a xenon fluoride atmosphere.