To allow a mediation agent who publicly opens the introduction information of lectures to be held by a plurality of lecture sponsors on a network to acquire a consideration corresponding to the provision results of the introduction information.

When introduction information from a user terminal 3-j to a certain lecture is requested, an information providing/mediating server 2 transmits the introduction information of the lecture, and transmits level check information for checking the level of a user and a level credit corresponding information indicating credits corresponding to the user. Then, the server 2 determines the level of the user based on an answer from a user terminal 3-j, and transmits it to the user terminal 3-j. The user is able to recognize receivable credits according to the level and the already transmitted level credit corresponding information. When the user is satisfied with the credits, the user transmits participation application to an information providing/mediating server 2. The information providing/mediating server 2 transmits the participation application to a lecture sponsor terminal 1-i of the sponsor who holds the lecture. The lecture sponsor terminal 1-i pays a prescribed consideration as the provision results of the lecture introduction information to a mediating agent.