A display device which displays an image on a cathode-ray tube screen based on video information decoded from a signal-compressed digital broadcast signal. The video information contains fields having a number of scanning lines which may change from field to field, potentially causing vertical jitter in the displayed image. A circuit prevents the vertical jitter by setting a same vertical scanning start position of an electron beam on the screen for all of the fields regardless of the number of scanning lines. The circuit may be a clamp circuit which clamps a vertical ramp waveform; or a control circuit which controls a direct current level of the vertical ramp waveform when the number of scanning lines in a current field is different from a reference number of scanning lines; or an amplitude control circuit which performs feedback control of an amplitude of the vertical ramp waveform.