The present invention provides a web site editing method, a web site editing system, and a web site editing computer program product enabling both an improvement in efficiency and safety in editing partial sites. A method of editing a web site by using a plurality of editing environments including at least first and second editing environments, the web site being composed of a plurality of web pages and stored in the first editing environment, the method in the first editing environment having: a specification step of accepting that a user specifies a part of the plurality of web pages as a partial site; and a generation step of generating an editing file including a specific file, which corresponds to the web pages included in the partial site, and a common file potentially used for editing the partial site.