Provided are an endoscope system and a method of operating the same capable of reliably performing focusing even in a case where an observation target is illuminated with light including long-wave light. A movable lens moves in an optical axis direction. A lens drive unit moves the movable lens from a first lens position of the movable lens where an observation target illuminated with short-wave light is focused to a second lens position of the movable lens where the observation target illuminated with long-wave light having a longer wavelength than the short-wave light is focused.