A framework for a business application system, which is used for constructing the business application system, is described by an object-oriented language having characteristics of abstraction and inheritance. The framework includes an abstract class group 10 having abstractly defined the structure and behavior of the business application system, and a common component group 20 including a plurality of common components commonly for use in the business application system. The abstract class group 10 includes a system core class group 11 having abstractly defined the basic structure and behavior of the business application system, and a screen system class group 12, a report system class group 13 and a business logic system class group 14, which inherit the system core class group 11. Thus, it is possible to provide a method for constructing a business application system, which can commonly use and reuse the basic structure of the overall business application system and which can flexibly and easily change and extend the business application system in accordance with a specification change.