1. A charged particle beam apparatus, comprising: a focused-ion-beam irradiation system for irradiating a sample with a focused ion beam, a deflection control system for deflecting said focused ion beam, a detector for detecting a secondary-particle signal emitted from said sample, an image generation unit for generating a scanning-ion-microscope image of said sample from a signal sent from said detector, a display apparatus for displaying said image generated by said image generation unit, an input apparatus for inputting an instruction from a user, and a manipulator, wherein: said deflection control system has beam deflection point resolution which is larger than display resolution by said display apparatus, and said image generation unit generates a scale pattern corresponding to repeated cells of said sample, when said sample includes said repeated cells, and superimposes said scale pattern on an image of said repeated cells of said sample, thereby extracting a microscopic area including a destination cell inputted from said input apparatus using the focused ion beam.