To provide an approval system associated with an approval workflow that identifies a signature document. A document management server for managing document data is connected with a client terminal (CLT) via an in-house LAN. Also, a seal to be affixed to a paper containing document specification information establishes a communication to the CLT. The seal reads the document specification information and user's fingerprint information and transmits the resulting pieces of information and impression information to the CLT. The document management server receives the document specification information, the fingerprint information and the impression information to confirm a coincidence between the received fingerprint and matching fingerprint and to confirm a coincidence between a set of the received document specification information and the received impression information and a set of matching document specification information and matching impression information, and to notify an approval situation to the CLT.