In a mono-light emission mode, specific illumination light is emitted and a specific observation image obtained from the image pickup of an object to be observed illuminated with the specific illumination light is displayed on a monitor 18. In a multi-light emission mode, first illumination light and second illumination light are emitted while being switched according to a specific light emission pattern and a first observation image and a second observation image are displayed on the monitor 18 while being switched according to a specific display pattern. In a case where a designated condition set in advance by a user is satisfied, a mode is automatically switched to the mono-light emission mode from the multi-light emission mode.
