An ion generator of an ion implanter is provided to reduce the amount of residual ions within an arc chamber and increase the amount of injecting ions by generating electric field to a slit direction. An arc chamber(310) includes a slit and forms an equipotential surface by a first voltage. A filament(311) is installed inside the arc chamber to generate electrons at a predetermined temperature. A plurality of magnetic field elements(321,322) are installed outside the arc chamber to generate the magnetic field within the arc chamber. A gas emission element(314) injects a predetermined gas into the arc chamber. An electrode is positioned opposite to the slit to generate the magnetic field within the arc chamber by a second voltage.
