In the image processing apparatus of the present invention, when a document is read, a document matching process section determines whether the document is similar to a reference document or not. When the document is similar to the reference document, the document matching process section further determines whether the document has been zoomed (size of the document has been changed). When the document has been zoomed, an editing process section restores the size of the document to the size of the reference document. This provides an image processing apparatus capable of restoring the changed size of a document in a predetermined format such as a form document and an application document to its original size.