Abstract: There is provided a system (1) comprising: a processing unit (11) equipped with execution modes including a non-secure mode (3) in which access to a protected region of a memory is prohibited by a support function (12) and a secure mode (2) in which access to the protected region is permitted; and a hypervisor (20) which runs in the secure mode. The hypervisor includes: a first setting unit (23) for setting a first operation condition (21), which includes enabling a first OS (30) running in the secure mode to access the protected region and the unprotected region of the memory; and a second setting unit (24) for setting a second operation condition (22a), which includes enabling a second OS (41) running in the non-secure mode to access the unprotected region, using the support function to prevent the second OS (41) from accessing the secure region, and enabling a transition to the secure mode by accessing of the second OS to a first device shared with the first OS.