1. A document processing method of processing document data which has chapters each including a plurality of pages, said method comprising the steps of: displaying preview screens for the plurality of pages included in the chapters of the document data; designating an inserting position in which an object is to be inserted; and recognizing a boundary between the chapters of the document data near to the inserting position designated in said designating step, wherein, in said display step, there is also displayed a mark which makes an operator distinguish which chapters on both sides of the boundary recognized in said recognition step, near which the object is to be inserted.