In an image processing apparatus which processes time-series images picked up by an imaging device in time series, a motion-vector calculating unit calculates a motion vector between plural images constituting the time-series images with respect to plural pixel regions set in the image. A newly-appearing-rate estimating unit estimates a newly-appearing rate which is a rate of a region newly appears in an image between plural images based on the motion vector. A display-time determination coefficient calculating unit calculates a display time of an image according to the newly-appearing rate.