1. A non-transitory computer-readable recording medium storing a document editing program for causing a computer to edit an electronic document including a plurality of hierarchically arranged objects, the program making a computer execute: extracting an object from the electronic document including the plurality of hierarchically arranged objects representing one of a text, an image, a drawing and a table; determining whether the extracted object is superimposed by a user specified area serving as a masking area of a target document input by a user; and converting, into different information, information included in an area of the object determined to be superimposed by the user specified area.
4. The non-transitory computer-readable recording medium storing a document editing program according to claim 1 , wherein the determining determines a superimposition area of the extracted object and an object hierarchically higher than the extracted object; and wherein the converting comprises converting information included in the superimposition area of the extracted object into the different information.