A tag database stores tag information corresponded to respective user identification information, shop identification information, and merchandise identification information. A tag management unit execute a tag mutual assignment process on a tag database that realizes a state where tag information is mutually assigned between user identification information and either shop identification information or merchandise identification information related to a mutual assignment target action. A tag processing unit, in response to a tag process target action in the user terminal, searches the tag database for tag information corresponded to user identification information, shop identification information, or merchandise identification information regarding the tag process target action, and acquires, based on extracted tag information, tag information or identification information used for generating presentation information to be transmitted to the user terminal. A presentation information generating unit, using the tag information or identification information acquired by the tag processing unit, generates the presentation information.