An analysis method of comparing documents and analyzing a changed part which does not match between the documents, the analysis method comprising: reading out first Extensible Business Reporting Language (XBRL) data and second XBRL data from a storage device, the first XBRL data including a first instance document that describes values of first items specified by item name, a first schema referred to from the first instance document, and first linkbases (231, 232, 233, 234, 235) that are referred to from the first schema and describe links between the first items, the second XBRL data including a second instance document that describes values of second items specified by item name, a second schema referred to from the second instance document, and second linkbases that are referred to from the second schema and describe links between the second items; analyzing the links between the first items described in the first linkbases to generate first link structure information (430, 440) that indicates parent-child relationships and sibling relationships between the first items; analyzing the links between the second items in the second linkbases to generate second link structure information (530, 540) that indicates parent-child relationships and sibling relationships between the second items; comparing item names of the first items defined in the first XBRL data with item names of the second items defined in the second XBRL data to detect a first unassociated item existing only in the first XBRL data and a second unassociated item existing only in the second XBRL data; comparing parent-child relationships and sibling relationships related to the first unassociated item with parent-child relationships and sibling relationships related to the second unassociated item, based on the first and second link structure information (430, 440, 530, 540); and associating the first unassociated item with the second unassociated item when the first and second unassociated items have a parent-child relationship or sibling relationship respectively with a specific first item and a specific second item, and when the specific first and second items have identical item names. reading out first Extensible Business Reporting Language (XBRL) data and second XBRL data from a storage device, the first XBRL data including a first instance document that describes values of first items specified by item name, a first schema referred to from the first instance document, and first linkbases (231, 232, 233, 234, 235) that are referred to from the first schema and describe links between the first items, the second XBRL data including a second instance document that describes values of second items specified by item name, a second schema referred to from the second instance document, and second linkbases that are referred to from the second schema and describe links between the second items; analyzing the links between the first items described in the first linkbases to generate first link structure information (430, 440) that indicates parent-child relationships and sibling relationships between the first items; analyzing the links between the second items in the second linkbases to generate second link structure information (530, 540) that indicates parent-child relationships and sibling relationships between the second items; comparing item names of the first items defined in the first XBRL data with item names of the second items defined in the second XBRL data to detect a first unassociated item existing only in the first XBRL data and a second unassociated item existing only in the second XBRL data; comparing parent-child relationships and sibling relationships related to the first unassociated item with parent-child relationships and sibling relationships related to the second unassociated item, based on the first and second link structure information (430, 440, 530, 540); and associating the first unassociated item with the second unassociated item when the first and second unassociated items have a parent-child relationship or sibling relationship respectively with a specific first item and a specific second item, and when the specific first and second items have identical item names.