To establish a relationship of trust at a content distribution market, maintain it, verify it, and make it improve; and to distribute contents smoothly and surely at the content distribution market.

By this disclosed content distribution support method, the system includes a plurality of mediation devices 1 which mediate distribution of contents, while managing a plurality of content offering devices 3 and a plurality of content use devices 2. When the content offering device 3 or content use device 2 which the mediation device 1 manages requests distribution of contents to other content offering device 3 or other contents use device 2 which other mediation device 1 manages, the mediation device 1 attaches an exclusive certificate which certificates that the system belongs to the corresponding community duly for every communities in which the content offering device 3 or the content use device 2 participates, and the other mediation device 1 authenticates the content offering device 3 or the content use device 2 which requests distribution of contents, based on the attached exclusive certificate.