An image file is managed more appropriately. When an image file is transferred from a camera to a server, a determination is made in advance as to whether or not an image file exists in both the camera and the server. When matching of image files is determined, an image file having the same file size is first identified. When an image file having the same size is present, partial hash values summarizing initial portions of the image files are then calculated. The partial hash values are compared with each other. When a match exists between the partial hash values, total hash values summarizing the entire image files are further calculated, and the total hash values are compared with each other. An image file having all of the same file size, the same partial hash value, and the same total hash value is determined to be an identical file. In contrast, the image file that is not matched in terms of any one of the three factors is determined to be another file, a request for transmission of the image file is sent to the camera.