There is provided an image processing device capable of increasing an observation efficiency by a user and an image processing method in the image processing device. The image processing device of the present invention includes: image signal input means for inputting an image signal based on a plurality of images obtained by medical equipment having an imaging function； image dividing means for dividing the plurality of images into a plurality of regions； feature value calculation means for calculating feature values in each of the plurality of regions； cluster classifying means for classifying the plurality of clusters generated in a feature space into any one of a plurality of classes, based on the feature value and occurrence frequency of the feature value and； subset generation means for generating a plurality of subsets using the plurality of images； and classification criterion calculation means for calculating a criterion of classification when classifying the image included in the one subset based on the distribution state of the feature value in the feature space of each image included in the one subset.
