A processor for an electronic endoscope includes first and second image storing units a motion detector obtains a difference of image data and a controller executes control in one of a first mode where the image data is sequentially converted into the video signal, and the image data and the difference are sequentially stored in the first and second image storing units a second mode where the image data stored in the first image storing unit is outputted, and the generated image data and the difference are sequentially stored in the second image storing unit and a third mode where the image data stored in the second image storing unit is outputted, and the generated image data and the difference are sequentially stored in the first image storing unit, and in the second and the third modes, based on the difference.