PURPOSE: To refer to an object module with a virtual storage shared among tasks by automatically detecting the object module used by plural tasks and allocating it to the same address in virtual storages characteristic to to respective tasks.

CONSTITUTION: The object module (OM) is inputted in a processing 5 and is registered in a task share entry table and a task proper entry table in accordance with the task shared attributes of each area, and the entry number is registered in OM entry table. In a processing 10, it is checked whether an OM to which said OM refers is already inputted or not. If it is registered by another task, plural reference flags in the task proper entry table are marked in a processing 20. The OM reference chain is updated in a processing. After the OM input processing of all tasks is terminated, entries to which plural reference flags in the task proper entry table corresponding are allocated to virtual memories characteristic to tasks in all tasks by a processing 39. In a processing, the entries in parts characteristic to tasks are allocated to virtual memories characteristic to tasks.