To provide the technique of advertisements for realizing the effective advertisements utilizing the bidirectionality of a computer network.

A sponsorship management part 104 makes respective participants select a sponsor from plural sponsor candidates and a competition management part 105 selects a competing opponent based on the desire of the participant and attributes specified beforehand by the sponsor, etc. A logotype/message management part 107 displays advertisement contents corresponding to the selected sponsor on a game screen corresponding to the participant. An affiliation index management part 110 calculates an evaluation value in the relation of the participant and the respective sponsors corresponding to the condition of participating in a game of the participant.