An ion implantation apparatus includes a beam scanner, a beam measurement unit that is able to measure an ion irradiation amount distribution in a beam scanning direction at a wafer position, and a control unit that outputs a control waveform to the beam scanner for scanning an ion beam. The control unit includes an output unit that outputs a reference control waveform to the beam scanner, an acquisition unit that acquires the ion irradiation amount distribution measured for the ion beam scanned based on the reference control waveform from a beam measurement unit, and a generation unit that generates a correction control waveform by using the acquired ion irradiation amount distribution. The control unit outputs the correction control waveform so that the ion irradiation amount distribution becomes a target distribution and the ion irradiation amount distribution per unit time becomes a target value.