An endoscope system is provided by which observation image brightness can be suppressed from irregularly fluctuating before and after changing of an observation mode and observers discomfort feeling can be reduced. The endoscope system includes an imaging element (21), an image processing section (65) that generates an observation image from an imaging signal, a display section (15) that displays the observation image, an illumination mode changing section (202) that changes illumination modes of a light source device, an image processing mode changing section (112) that changes an image processing mode, and a light source control section (55, 355) that controls the light source device.
