This invention provides a technique to correctly inform the human being of content of contents to be published but to prevent machines from collecting part of the contents whose distribution is not desired by the information provider. This invention includes: reading out contents data to be published, which includes text data, and identifying a character string whose output as the text data should be avoided from the contents data; converting the identified character string into substitution data other than the text data so as to maintain content of the identified character string; and generating publication contents data to maintain publication content of the contents data by using data other than the identified character string in the contents data and the substitution data. Thus, by carrying out such a processing, it becomes possible to conceal the character string against machines without changing the publication content for the human being.