.[.As to an object-oriented programming, reuse of softwares is enhanced and running speed is improved. There are made up a data element list in which pointers to data storage areas of object A are arranged and a pointer element list in which pointers to pointer storage areas of object B are arranged. A combination of the data element list and the pointer element list makes it possible to directly refer to data of the object A from the object B..]. .Iadd.Object-oriented programming is performed by displaying objects connected by wirings that represent the flow of data, control or messages from one object to a second object. A coupling of input and output terminal so that objects is shown by displaying a wiring between the terminals. A coupling structure is constructed in accordance with the wiring within an object hierarchy, so that instructions to rearrange, duplicate or replace objects may be permitted. The display is preferably divided into domains, for the respective display of the objects and the wiring. When displaying a subnetwork of a predetermined object, a second image is used to display a more enlarged display area..Iaddend.