A portable information terminal is separated from a charged particle beam irradiation apparatus for performing processing of a sample by irradiating the sample with a charged particle beam. The portable information terminal performs operation of a first operation item at a desired position and includes a display controller causing a display unit to display an image containing a graphical user interface (GUI) capable of operating the first operation item based on operation by a user, the first operation item being one or more operation items among a plurality of items operable in the charged particle beam irradiation apparatus.