1. An inadequately trimmed image detection method for detecting an inadequately trimmed image generated by failure of automatic trimming processing among a large amount of trimmed images in a predetermined size generated by the automatic trimming processing wherein a trimming range is cut and/or scaled from respective photographs obtained by photography of subjects of the same type so that a target part to be trimmed is laid out in a predetermined position in a predetermined size in the trimming range, the inadequately trimmed image detection method comprising the steps of: carrying out serial reproduction of the trimmed images in a predetermined position at a predetermined image display rate; and carrying out marking processing for identifying an image group including the inadequately trimmed image, based on input representing finding of the inadequately trimmed image during the reproduction.