A system retrieves structured documents based on first desired concept item having first concept items classified hierarchically and subordinated to first desired concept item, second desired concept item having second concept items classified hierarchically and subordinated to second desired concept item, generates a table displaying retrieval results, and associates groups of desired component, one of first items classified as first concept items immediately lower than first desired concept item, and desired second concept item with column index cells of table respectively. When a display area where one of the column index cells is displayed is designated, the system acquire the groups associated with the designated area, and retrieves, based on the acquired group, structured documents each including the desired component including a value in which one of the first concept items subordinated to the one of the first item and one of the second concept items are included.