PURPOSE: To increase reproductivity of ion generation by forming a pyramid- shaped protruded section at the lower part of the electrode main body of a single crystal substance on the upper surface side of which the collection section of fused ion generation raw material is provided and providing a penetration hole which leads the ion generation raw material to the tip of the protruded section.

CONSTITUTION: A pyramid-shaped protruded section 10a is provided at the lower prt of an electrode main body 10 consisting of silicone single crystal substances by anisotropy etching and a collection section 11 is formed on the upper part except the peripheral section by etching. Four penetration holes 12 are provided at the lower part of the electrode main body 10 between the peripheral section of the protruded section 10a and collection section 11 and an ion generation raw material 7 is housed in the collection section 11. An external electrode 5 is arranged at the lower part of the main body 10 and a power source 6 is connected. As a result, the shape and diameter of each section can accurately be preset and the reproductivity of ion generation be improved.