A wafer processing apparatus includes a chamber, and a voltage waveform generator configured to accelerate plasma ions of the chamber, the voltage waveform generator includes: a pulse circuit configured to apply a chamber voltage, which is a pulse voltage, to the chamber by adjusting a chamber current applied to the chamber; and a slope circuit configured to generate a slope in an on-duty of the chamber voltage, which is the pulse voltage, and the pulse circuit includes a first inductive element configured to store a first internal current.