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 sequential reproduction of the trimmed images on a display screen in a predetermined position of the screen at a predetermined image display rate; and carrying out marking processing for identifying an image group including the inadequately trimmed image, based on a user input indicating a finding by the user of the inadequately trimmed image during the reproduction, wherein the predetermined image display rate ranges from 10 images per second to 50 images per second, and wherein the marking processing is processing for identifying the trimmed images reproduced in a predetermined time range before the input as the image group.