There is provided an image processing device comprising a processor, in which the processor acquires a plurality of endoscopic images obtained by picking up images of an observation target with an endoscope, calculates a raw score related to a determination of a severity or a stage of a disease of the observation target, on the basis of each of the endoscopic images, decides a final score on the basis of the raw score, and performs control to display the final score and/or a change over time of the final score in real time on a display.