PURPOSE: To obtain a high frequency inductive coupling plasma-mass spectrometer of high sensitivity by generating the discharge by a fixed voltage applied the electrodes provided near the top of a skimmer.

CONSTITUTION: When a fixed voltage from a variable voltage power supply 53 is applied to the electrodes 52, electrons are accelerated toward the electrodes 52 and energy of the electrons become greater than ionization energy of surrounding electrons. By this, the discharge is generated around the electrodes 52, i.e. around the top of a skimmer 5, and light is emitted. On the other hand, atoms (elements, etc., to be measured) which are not ionized in a plasma are also pulled into a nozzle 4 together with ions in the high frequency inductive coupling plasma 6 and passed through the discharging area. Thus, the atoms not ionized in the plasma 6 are now ionized by the discharge, amount of the ion pulled into the skimmer 5 becomes greater than the ions in the plasma 6 so that sensitivity of the high frequency inductive coupling-mass spectrometer can be increased.