An ion implantation device equipped with a vacuum chamber (11), an electrode roll (13) on a portion of the outer circumferential part of which a film (2) is wound, a voltage application means (21) that applies a voltage to the electrode roll, and a gas introduction means (31) that introduces a gas into the vacuum chamber, wherein a voltage is applied to the electrode roll by means of the voltage application means and a gas is introduced by means of the gas introduction means, and an ion implantation process is performed on the surface of the film. In addition, electrode members (42) are provided opposing the surface of the electrode roll on which the film is wound.