PURPOSE: To perform the access of a data base part with a natural language, by using a definition file defined preliminarily at the time of execution, and substituting a fundamental word for a word, or a sentence in the natural language.

CONSTITUTION: The fundamental word corresponding to the natural language is stored preliminarily in the definition file, and when the word that is not the fundamental language is inputted at the time of execution, by executing a process by substituting the fundamental word for that word if the presence of that word in a definition file part 5 is investigated, a user accesses a data base part 6 based on the natural language. When the word that is not the fundamental word is inputted, the definition file part 5 is investigated, and it is possible to substitue a corresponding fundamental word for that word if the word is already registered.