A business requirement handling apparatus is adapted to a data processing system which includes a central processing unit, a display unit and an input unit. The business requirement handling apparatus is provided with a business requirement database accumulating and managing business requirements of businesses to be programmed depending on a substrate indicating predetermined data types and relations thereof, business requirement editing process device displaying business requirements on display unit to perform editing process and storing edited business requirements in business requirement database in units of individual data types, where each of business requirements are described in the form of a restricting expression which restricts input data if a processing content is formed of input items, described in the form of a calculation expression for obtaining output data if the processing content is formed of output items, and added with a conditional expression if a necessary condition exists, a contradiction detecting process device detecting existence of contradictions among the business requirements stored in business requirement database based on attributes including restricting expression, calculation expression or conditional expression annexed to items of business requirements, and notifying a user of content of contradiction when contradiction is detected, and a program synthesizing process device generating program parts from requirements of each item based on business requirements stored in business requirement database, and generating business program which is executable in a user environment by synthesizing the program parts with a given control logic.