A usage information storage section is configured to store usage information. An item information storage section is configured to store attribute correspondence information. A relevant attribute selection section is configured to calculate an attribute relevant degree based on the usage information and the attribute correspondence information, select a relevant attribute for each item identifier based on the calculated attribute relevant degree, and create relevant attribute information in which each item identifier and the selected relevant attribute are associated with each other. A relevant item selection section is configured to acquire attribute correspondence information including any attribute identifier included in the relevant attribute information, calculate a relevant degree between each item identifier included in a relevant candidate item aggregate as an aggregate of item identifiers included in the acquired attribute correspondence information and a reference item, and select an item relevant to the reference item based on the calculated relevant degree.