To set an appropriate brightness of images displayed on a monitor all the time if the magnification setting is varied in a device or a system described above with an electronic zoom function.

A processor comprises a light source for emitting illumination light supplied to an electronic endoscope, a light quantity adjusting means capable of adjusting the light quantity, a magnification setting means for setting a magnification, an image information extracting means for extracting information of the image to display the image at the set magnification, and a light controlling means for controlling the light quantity adjusting means from the brightness information included in the extracted image information.