It is possible to reduce a review load of a reviewer. A document management system includes a screen display unit that displays a document group having a plurality of pieces of document data extracted from digital information to be determined for relevance to a lawsuit by a user and classification buttons allowing the user to select classification conditions for classifying the document group under predetermined conditions, a selection information reception unit that receives information relating to a classification button selected by the user among the classification button displayed by the screen display unit as selection information, and a classification instruction unit that analyzes the document group based on the selection information, classifies document data in the document group using the analysis result, and instructs the screen display unit to display the document group based on the classification result.