There is provided a document management server including a receiving unit that receives from a client a request and a first ID representing a document, an ID processing unit that issues, when an operation is performed on the document, a second ID, and records a derivation relationship having the second ID as a child of the first ID, a base node setting unit that sets a base node to indicate a division of a user among a node group in the derivation relationship, a document associating unit that associates related data of the document registered by an operation corresponding to a descendent node of a base node to the base node, and a document provider unit that provides, when receiving a user request for a digital document, detects a base node by tracing the derivation relationship from an ID accompanying the request to the root node, and provides the requested document based on related data associated to the detected base node.