An ion emmisive head for fusing a metal to emit ion beam is disclosed, wherein a fused metal is designed to infiltrate through a porous portion for flow control and to reach an extremely sharpened needle which is provided after infiltration and wherefrom the fused metal is converted to ion beam by electrical action. Thus, ionized metallic beam is rendered to have smaller width or more focused ray. Submicron technology used in the IC industry, for instance, desires far thinner, finer beam line to attain more compact circuits, which need will be responded in the present invention by disposing a tipping needle to extend out of a porous tip portion which receives the fused metal from melting zone. Appropriate combination of sharpness at the needle point and provision of a beam guiding electrode in neighborhood of an emitting needle point enable to produce about 0.1 micron beam width by prevention of plasma ball which will otherwise diffuse the emitted beam.