1. An image processing device comprising: an instruction acquiring section configured to acquire an instruction input by a first user; an image group selecting section configured to select, as a second image group, a part of images from a first image group owned by the first user based on the instruction; an image analyzer configured to carry out image analysis on images contained in the first image group based on a first judgment criterion; and an image group extracting section configured to extract, as a third image group, at least a part of images having relevance to images contained in the second image group from the first image group except the second image group based on a result of image analysis on images contained in the first image group, wherein the image group extracting section extracts, as a fourth image group, images having relevance of a value not smaller than a first threshold value to images contained in the second image group from the first image group except the second image group based on a result of image analysis on images contained in the first image group, the image analyzer further carries out image analysis on images contained in the second image group and the fourth image group based on a second judgment criterion that is higher than the first judgment criterion, and the image group extracting section extracts, as the third image group, images having relevance of a value not smaller than a second threshold value that is higher than the first threshold value to images contained in the second image group from the fourth image group based on a result of image analysis on images contained in the second image group and the fourth image group.