To provide a document management device for enabling a user who has edited a document in the past to receive update notification when any part relevant to the part edited by the user himself or herself has been changed.

A document storage part 24 stores a structured document. An updated part extraction means 27 extracts a sentence structure element changed between the documents before and after version update by referring to the document storage part 24. A update part extraction means 27 stores the update information including the extracted changed sentence structure element in association with the document after the version update into an update information storage part 28. A notification object determination means 29 specifies the version of the document whose sentence structure element relevant to the sentence structure element changed in the document after the version update has been edited by referring to the update information, and determines the user who has edited the document of the version as a notification object user. An update notification means 23 notifies the notification object user that the document has been updated.