A document management system includes: a document to which an information storage medium is attached; an information storage medium reading device which includes a reading unit for reading document identification information and a unit for transmitting a signal to a processing device when the document identification information becomes unreadable; a portable information storage medium; a first portable information storage medium reading device; a second portable information storage medium reading device; a locking/unlocking device; and an information processing device. The information processing device includes a document information database; a taking-off document specifying unit which specifies the document identification information of the document based on the document information database; a determination unit which determines the taking-out authority from individual identification information which is received from the first portable information storage medium reading device and the document identification information; and a unit which transmits a signal for unlocking a lock state to the locking/unlocking device in such a case that a person has a taking-out authority at a time of receiving the individual identification information from the second portable information storage medium reading device.