The invention aims to provide a document administration apparatus for processing input original data, which comprises: a first memory for storing the original data; a mask data generator for generating mask data capable of masking at least one predetermined area of the original data; a second memory for storing the mask data generated by the mask data generator; a selector enabling to select the original data stored in the first memory and the mask data stored in the second memory; a display enabling to display the mask data selected by the selector in a state that the mask data is superposed on the original data, without changing the original data selected by the selector; and a mask data editor enabling to edit the mask data displayed on the display in the state that the mask data is superposed on the original data.