A high voltage power supply, comprising: a switching unit that is driven in accordance with a frequency signal; a voltage resonant unit that is connected to the switching unit and includes an inductor, to which a voltage is applied when the switching unit is driven, and a capacitor; a multi-stage rectifier unit including a plurality of rectifier units each having a diode (D101,D102,D103,D104,D105) and a capacitor (C101, C102, C103, C104, C105), wherein the multi-stage rectifier unit is connected to the inductor and configured to amplify a voltage generated in the inductor; and a voltage output unit that outputs the voltage (Vout1) amplified by the multi-stage rectifier unit, characterized by a frequency control unit that controls a frequency of the frequency signal in accordance with a control signal used to set a voltage output and an output signal (Vout2) corresponding to the voltage output, wherein the frequency signal is a rectangular wave signal, wherein the switching unit is turned on in a case where the rectangular wave signal is high, and the switching unit is turned off in a case where the rectangular wave signal is low, wherein the frequency control unit controls an on time when the rectangular wave signal is high to be a first time in a case where a voltage output from the voltage output unit is a first voltage, and controls the on time when the rectangular wave signal is high to be a second time longer than the first time in a case where a voltage output from the voltage output unit is a second voltage higher than the first voltage, wherein the plurality of rectifier units includes a first rectifier unit connected to the switching unit and a second rectifier unit connected to the first rectifier unit, and the high voltage power supply further comprises a second voltage output unit that outputs a voltage (Vout2) obtained from the first rectifier circuit, wherein said second voltage output unit includes a capacitor and a constant voltage element connected between the first rectifier unit and the capacitor, wherein the output signal (Vout2) is a feedback signal output from said second voltage output unit, and wherein the frequency control unit controls the frequency of the frequency signal in accordance with the control signal (Vcont) and the feedback signal. a switching unit that is driven in accordance with a frequency signal; a voltage resonant unit that is connected to the switching unit and includes an inductor, to which a voltage is applied when the switching unit is driven, and a capacitor; a multi-stage rectifier unit including a plurality of rectifier units each having a diode (D101,D102,D103,D104,D105) and a capacitor (C101, C102, C103, C104, C105), wherein the multi-stage rectifier unit is connected to the inductor and configured to amplify a voltage generated in the inductor; and a voltage output unit that outputs the voltage (Vout1) amplified by the multi-stage rectifier unit, characterized by a frequency control unit that controls a frequency of the frequency signal in accordance with a control signal used to set a voltage output and an output signal (Vout2) corresponding to the voltage output, wherein the frequency signal is a rectangular wave signal, wherein the switching unit is turned on in a case where the rectangular wave signal is high, and the switching unit is turned off in a case where the rectangular wave signal is low, wherein the frequency control unit controls an on time when the rectangular wave signal is high to be a first time in a case where a voltage output from the voltage output unit is a first voltage, and controls the on time when the rectangular wave signal is high to be a second time longer than the first time in a case where a voltage output from the voltage output unit is a second voltage higher than the first voltage, wherein the plurality of rectifier units includes a first rectifier unit connected to the switching unit and a second rectifier unit connected to the first rectifier unit, and the high voltage power supply further comprises a second voltage output unit that outputs a voltage (Vout2) obtained from the first rectifier circuit, wherein said second voltage output unit includes a capacitor and a constant voltage element connected between the first rectifier unit and the capacitor, wherein the output signal (Vout2) is a feedback signal output from said second voltage output unit, and wherein the frequency control unit controls the frequency of the frequency signal in accordance with the control signal (Vcont) and the feedback signal.