A document analysis device (1) comprises a common assessment information selection unit (90) and an event impact analysis unit (100). The common assessment information selection unit (90) identifies information that matches second assessment information that appears in event-related documents which include descriptions concerning a designated specific event, from among first assessment information that appears in documents for analysis which include descriptions relating to items for analysis, and classifies the information thus identified as common assessment information. The event impact analysis unit (100) counts the number of times the common assessment information appears in the documents that are generated prior to the event occurring, and the number of times the common assessment information appears in the documents for analysis that are generated subsequent to the event occurring, and derives an index that denotes the impact of the specific event upon the documents for analysis, on the basis of the results of the counts thereupon.