1. An image processing device comprising: a facial image extraction portion that specifies a facial region of an imaged subject within at least one sequentially input selection-eligible image and extracts from the selection-eligible image a facial image that corresponds to the facial region; a positivity computation portion that computes for each selection-eligible image, using the facial image, a positivity of the imaged subject toward a person who acquired the at least one selection-eligible image; and a selected image update portion that compares each selection-eligible image for which the positivity was computed in the positivity computation portion to a selection candidate image that has a greatest positivity among all the selection-eligible images for the same imaged subject for which the positivities have already been computed, and makes the image with a greater positivity a new selection candidate image.