PURPOSE: To prevent deterioration of ion beam convergence, isolate a low energy beam from a high energy beam, and converge an ion beam on a substrate to be irradiated with said beam.

CONSTITUTION: The title equipment is provided with the following; an ion source 11 arranged in a vacuum vessel 10, an ion beam leading-out electrode 12 which leads out ions emitted from the ion source 11, an analytical magnet 13 which selects specified ion seeds from the ion beam led out by the leading-out electrode 12, and a deceleration electrode 14 which decelerates the ion beam selected by the analytical magnet. An electric field reflection type lens 20 which reflects a low energy beam and transmits a high energy beam is arranged on the post- stage of the deceleration electrode 14. A substrate 30 to be treated is irradiated with the Low energy ion beam or the high energy ion beam which can be obtained via the lens 20.