A document generating system which includes an input device for inputting document data, a heading candidate extraction section for extracting, as a heading candidate, the word corresponding to the heading stored in a heading dictionary from the document data input at the input section. A heading decision section is implemented in the system for checking the heading candiate, that was extracted by the heading candidate extraction section according to a heading rule stored in a heading rule dictionary and for deciding whether the heading candidate is a heading. Also, a document architecture decision section is implemented in the system for checking the heading decided by the heading decision section according to document architecture rules stored in a document architecture rule dictionary. The architecture decision section is for determining the heading as satisfying the document architecture rule as a true heading, and the heading not satisfying the document architecture rule as being false heading.