In a flat panel display device configured to allow moving image data supplied through a signal line 11 to be written to a pixel electrode 13 during typical display operation and further to allow still image data latched in a digital memory 18 to be written to the pixel electrode 13 during still image display operation. When switching from a typical display to a still image display, at least two frames following the completion of the switching operation are assigned as write frames to allow still image data to be written to the digital memory 18. This allows the still image data to be written normally to the digital memory 18 even when the rise times of a memory control signal and a common signal are made longer than a vertical blanking period.