A processor for an electronic endoscope includes first and second image storing units and a controller, which in a first mode, image data is converted sequentially into a video signal and is outputted while being stored sequentially in the first and second image storing units. In a second mode, image data stored in the first image storing unit is outputted while generated image data is sequentially stored in the second image storing unit. In a third mode, image data stored in the second image storing unit is outputted while generated image data is sequentially stored in the first image storing unit. In the second and third modes, it is possible to switch between a first playback mode that continuously outputs the multiple stored image data and a second playback mode that repeatedly outputs one of the multiple stored image data.