Metadata items commonly included in all sets are specified and displayed as common metadata items. When the user selects one of the displayed common metadata items as a designated common metadata item, metadata values in respective sets of an item indicated by this designated common metadata item are classified to any of a plurality of classification items determined based on the set condition. The plurality of classification items are list-displayed. When the user selects one of these plurality of classification items as a selected classification item, icons of contents data as sets with the metadata values classified to this selected classification item, and common metadata items other than the designated common metadata item of the displayed common metadata items are displayed.