In the method for sharing encrypted data region among two or more processes on a tamper resistant processor, one process creates the encrypted data region to be shared according to the common key generated as a result of the safe key exchange, and the other process maps that region to its own address space or process space. The address information of the shared encrypted data region and the common key of each process are set in relation in the encrypted attribute register inside the tamper resistant processor, so that it is possible to share the encrypted data region safely.