A combined field ion (FIM) and scanning tunneling microscope (STM), which is called ‘‘FI–STM,’’ was designed, constructed with multiple surface analytical functions. The instrument has been operated successfully by observing the detailed structures of the graphite (0001) and the Si(111)7×7 surfaces. The FI–STM is equipped with a low-energy electron diffraction/Auger electron spectroscopy system and a sputtering gun and/or heating devices for preparing and characterizing specimen surfaces. The field ion microscope is operated at room temperature to observe the geometry of the STM scanning tip in situ in the course of STM investigations.