There is provided a document processing device and a document processing method capable of aligning and loading documents being transported surely and at a high speed. The document processing device includes: a document inverter for inverting a transport direction of documents being transported; a first guide that is provided in nearly the same direction as the transport direction positions document stacked layers when stacking documents inverted by the document inverter; a second guide that is provided to further tilt at a predetermined angle than orthogonal angle to the transport direction and capable of guiding the transported documents in the first guiding means direction, positions document stacked layers when stacking documents inverted by the document inverting means in conjunction with the first guiding means; and a holder for loading and holding the documents positioned and stacked by the first guide and the second guide. The second guide is constituted by a flat transported document abutting surface capable of making ends of the documents being transported slide down in a positioned state.