1. An apparatus for maintaining security of scanned documents, said apparatus comprising: a scanned document data registering part that receives image data corresponding to a scanned document read in a read operation by a read apparatus and registers read operation data indicating (i) user identification of a requesting user requesting the read operation, (ii) a time of the read operation and (iii) device identification of the read apparatus that performed the read operation; an access information database that registers, for each user amongst plural users, user access information indicating documents accessible by the specific user; a document status determining part that determines based on at least one of (i) the received image data and (ii) the user access information obtained from the access information database whether the scanned document includes proprietary or confidential information, and in a case that the document status determining part determines that the scanned document includes proprietary or confidential information, generates unique identification data corresponding to the read operation, and causes the scanned document data registering part to register the unique identification data along with the read operation data in a secured storage unit; an output part that outputs output data, based on the image data and in response to an output request requesting output of the scanned document, to a specified destination; a user interface displaying part that displays a user interface to the requesting user and receives user input from the requesting user through the user interface; and an operation monitoring part that monitors operations of the read apparatus and operations of the output part, wherein in a case that the document status determining part determines that the scanned document requested to be output by the output request includes proprietary or confidential information, the operation monitoring part causes the user interface displaying part to display a warning message through the user interface, the warning message requesting confirmation that output of the scanned document that includes proprietary or confidential information is desired, and upon receiving the confirmation through the user interface that the output of the scanned document that includes proprietary or confidential information is desired, causes the output part to output the output data for an output image that includes the read operation data shown in combination with an image of the scanned document.