Because noble gases are chemically inert, scarce in the earth and meteorite (except ⁴⁰Ar in the earth’s atmosphere), and highly volatile, their isotope ratios have provided important insights in research fields of earth, planetary, and environmental sciences. The progress of noble gas geochemistry and cosmochemistry has been paced by the rate of developments in mass spectrometry. In this contribution, the history and basic principles of noble gas mass spectrometry and general techniques used in most modern laboratories are overviewed. The noble gas mass spectrometry has developed with inventions of various techniques—Nier type electron ionization (EI) source, static mode operation under ultrahigh-vacuum, adequately high resolution to distinguish very minor noble gas isotopes from interferences, and numerous small tips accumulated in laboratories—to attain increasingly greater precision to distinguish the often subtle variations in isotopic compositions, higher sensitivity to measure the low abundances found in many materials, and lower blanks to remove interference from atmospheric gases. New technologies recently exploited, such as simultaneous detection of noble gas isotopes with multicollector detection system, high-transmission EI source, resonance ionization, compression EI source, post-ionization of sputtered noble gases by focused ion beam, which enable us to detect quite small amount of noble gases down to several thousands of atoms, are opening new era of noble gas mass spectrometry. The highly-sensitive noble gas mass spectrometry can be applied to continuous monitoring of activity of volcanoes or active faults and to detect trace amount of noble-gas producing elements upon neutron irradiation, such as halogens, potassium, calcium, uranium, etc.