An endoscope system includes: an insertion portion configured to be inserted into an inside of an object; a forward observation window configured to acquire a forward field-of-view image; a lateral observation window configured to acquire a lateral field-of-view image; and a control portion. The control portion detects an amount of change in an image signal in a predetermined judgment area in at least one of the forward field-of-view image and the lateral field-of-view image within a predetermined time period, judges a use state of the insertion portion based on a result of the detection, and controls an image signal of the forward field-of-view image and an image signal of the lateral field-of-view image to be outputted to a monitor capable of displaying the forward field-of-view image and the lateral field-of-view image, according to the judged use state.