To provide a method of changing a graphic user interface controlled by an operation system for customizing in manufacture of a computer system.

The changing method of a graphic user interface includes steps of reading a constitution file 220 related with the operation system, reading an install program 320 in response to this reading and adding graphic video to the graphic user interface in the middle of calling at the beginning of the operation system by a user. Then, the graphic video to be added is related with an application program and is added with the result of calling the install program and the graphic video appearing in the first display of the graphic user interface with respect to the user.