A deflecting voltage generating circuit comprising a voltage generating unit for generating a deflecting voltage and a voltage correcting unit for correcting the deflecting voltage generated by the voltage generating unit and applying the deflecting voltage thus corrected to deflecting electrodes of a streak tube, a sampling streak tube or the like. The voltage correcting unit is so designed that for a predetermined period from the time instant when the deflecting voltage changes, the deflecting voltage is not applied to the deflecting electrodes, and immediately after the lapse of the predetermined period the deflecting voltage is applied to the deflecting electrodes.