A document anonymity setting device comprises a document input means inputting a document, a specificity calculating means extracting an expression specifying a person from the input document and for calculating a specificity to evaluate a degree of specificity at which the expression specifying a person, and an anonymity setting processing means rewriting with anonymity setting a expression in the input document having a specificity which is greater than a predetermined threshold. The specificity calculating unit extracts a person name and a modification expression from the input document and calculates a specificity to evaluate a degree of specificity at which the person name and modification expression thus extracted can specify a person. The anonymity setting processing unit rewrites a person name and a modification expression which have a specificity greater than a predetermined threshold through rewriting to meaningless expression, rewriting to low specificity setting, and rewriting to encrypted expression.