An ion implantation apparatus includes a first angle measuring instrument configured to measure angle information on an ion beam in a first direction, a second angle measuring instrument configured to measure angle information on the ion beam in a second direction, a relative movement mechanism configured to change relative positions of the first angle measuring instrument and the second angle measuring instrument with respect to the ion beam in a predetermined relative movement direction, and a control device configured to calculate angle information on the ion beam in a third direction perpendicular to both a beam traveling direction and the relative movement direction based on the angle information on the ion beam in the first direction measured by the first angle measuring instrument and the angle information on the ion beam in the second direction measured by the second angle measuring instrument.