An endoscope system of the present invention has an endoscope which acquires a direct-view field of view image and a side-view field of view image of an object to be observed, a light source apparatus which supplies an illuminating light for illuminating the object to be observed, a detection section which detects a change of a physical quantity with respect to movement of an insertion section provided at the endoscope, which occurs due to an operation of the endoscope, an image processing unit which generates and outputs a video signal including the direct-view field of view image and the side-view field of view image in a same screen, and a light adjustment area selection section which detects a brightness of the direct-view field of view image and a brightness of the side-view field of view image individually, selects a field of view image corresponding to a moving direction in which the change of the physical quantity increases out of the direct-view field of view image and the side-view field of view image as a light adjustment target based on a detection result of the detection section, and performs control so as to make a luminance of the field of view image selected as the light adjustment target relatively higher than a luminance of the other field of view image.