To provide a document sharing system enabling each participant to share a document to be used even in a public event by a simple operation.

This ad hoc conference support system 10 for sharing the documents of event participants is provided with: an IC card recognizing and writing means 21 for generating context information, and for writing it in a portable telephone 30 including a storage means carried by the participant when an event is held; and a shared document storing and disclosing means 43 for disclosing document data owned by the participant on a personal PC 40 information processing terminal as shared document data on a network based on a document sharing request using context information generated when the event is held, and written in the portable telephone 30 carried by the participant, and for providing the shared document data disclosed on the network based on the document request using the context information.