An ion implantation method includes transporting ions to a wafer as an ion beam, causing the wafer to undergo wafer mechanical slow scanning and also causing the ion beam to undergo beam fast scanning or causing the wafer to undergo wafer mechanical fast scanning in a direction perpendicular to a wafer slow scanning direction, irradiating the wafer with the ion beam by using the wafer slow scanning in the wafer slow scanning direction and the beam fast scanning of the ion beam or the wafer fast scanning of the wafer in the direction perpendicular to the wafer slow scanning direction, measuring a two-dimensional beam shape of the ion beam before ion implantation into the wafer, and defining an implantation and irradiation region of the ion beam by using the measured two-dimensional beam shape to thereby regulate the implantation and irradiation region.