According to one embodiment, a document processing apparatus includes an acquisition unit, an extractor, and a detector. The acquisition unit acquires a first document and a second document different from the first document. The extractor extracts a first structure representing a word dependence of structural elements in the first document and extracts a second structure representing a word dependence of structural elements in the second document. The detector detects a difference for each structural element from the first structure and the second structure.