A video processor that is connectable to an endoscope and an external light source device that supplies illumination light to a light guide of the endoscope includes: a connection detector that detects a presence/absence of connection between the video processor and the light guide of the endoscope; an internal light source unit that supplies the illumination light to the light guide of the endoscope; a communication controller that performs communication with the external light source device, and obtains device data of the external light source device; and a utilized light source determination unit that determines a light source that supplies the illumination light to the light guide of the endoscope in accordance with a detection result of the connection detector or a state of obtainment of the device data of the communication controller.