To facilitate the design of each program module constituting of a simulation system that simulates the operation of a device consisting of plural elements performing input-output with one another.

When respective I/O simulation modules 103 and 104 are started, the correspondence of a self-I/O simulation module to an address range allocated to an element corresponding to the self-I/O simulation module is registered with a management module 102. When the modules 103 and 104 perform input- output, they issue an inquiry designating an address range to be an object of the input-output to the management module and issue an input-output request to an I/O simulation module responding to the input-output request. The module 102 answers a registered I/O simulation module in accordance with an address range including the address range designated by the inquiry.