An ion implanter for manufacturing a single crystal film by extracting a hydrogen ion or a rare-gas ion from an ion source, selects a desired ion with a first sector electromagnet, scanning the ion with a scanner, collimates the ion with a second sector electromagnet, and implants it into a substrate; the ion source is configured to be located close to the entrance side focal point of the first sector electromagnet. In this case, when an aperture of an extraction section of the ion source is circular and entrance side focal points in a deflection surface and a surface perpendicular thereto in the first sector electromagnet are coincident, the ion beam after passing the first sector electromagnet becomes completely parallel in the two surfaces and the spot shape becomes a circle.