1. An image processing device, comprising: an image signal input portion for inputting an image signal on the basis of a plurality of images obtained in a time series by medical equipment having an imaging function; an image dividing portion for dividing the plurality of images into a plurality of regions, respectively, on the basis of the image signal inputted in the image signal input portion; a feature value calculation portion for calculating one or more feature values in each of the plurality of regions divided by the image dividing portion; an image region classifying portion for classifying each of regions into any one of the plurality of classes on the basis of the feature value; a representative value calculation portion for calculating a representative value of the feature value of at least one class in each of the plurality of images; and a variation detection portion for detecting variation in the representative value in a time series.