To improve the extensibility and reusability of a program, to improve visuality and to improve maintenance by exchanging an initialization program in accordance with a program to be executed in the initial stage of the exectuion of the individual programs.

A data initialization program storage part 33 stores the initialization program which respective objects require. In the execution initial stage of the individual programs, a program initialization device 4 exchanges the initialization program in accordance with the program to be executed. Thus, the call of the method of the object in a low-order class at the time of stepwise access restriction and virtual function call in inter-process common data is optimized. Furthermore, additional information which differ for the respective objects and are required can efficiently be given so that restrictive description on the program becomes a minimum.