1. An image processing device comprising: an image acquiring section configured to acquire a moving image and a plurality of still images; a characteristic information extractor configured to extract, from the plurality of still images, at least a number of times a same subject appears in the plurality of still images, as characteristic information; a target object detector configured to detect a subject which appears a number of times not less than a first threshold value, as a target subject; an image analysis condition determiner configured to set an image analysis condition for a portion of the moving image where the target subject is absent to be rougher than the image analysis condition for a portion of the moving image where the target subject is present; a frame image analyzer configured to extract frame images from the moving image and perform image analysis on the extracted frame images in accordance with the image analysis condition; and a frame image output section configured to calculate an evaluation value of each of the frame images based on a result of the image analysis and output, of the frame images, a frame image having an evaluation value not less than a second threshold value.