A radio-frequency voltage generator includes a first DC power supply for generating first direct-current voltage; a second DC power supply for generating second direct-current voltage; a transient alternating voltage generation circuit for generating a transient alternating voltage having a cycle shorter than a cycle of the radio-frequency voltage and having a voltage value oscillating between the first direct-current voltage and the second direct-current voltage; and a voltage switch section for switching voltages from the first direct-current voltage, to the transient alternating voltage, to the second direct-current voltage, and to the transient alternating voltage in this order, wherein the voltage switch section switches the voltages applied to the load so that the transient alternating voltage oscillates a half-integer of times starting with an initial value having the value of the direct-current voltage applied immediately before the switching, the half-integer being equal to or greater than 1.5.