A secret information processing apparatus including: a control unit 102 storing access control levels assigned to resources in the apparatus and used as a standard in judging whether to permit an access to any resource from any external apparatus; a secret information storage unit 105 storing an update target program; and an internal CPU 103 that performs an update process for updating the update target program if an update request is received. The control unit 102 determines whether to permit accesses to the resources from the external apparatus, in accordance with the access control levels. The internal CPU 103 changes, during the update process, access control levels of resources, which are to be accessed by the update unit during the update process and whose access control levels indicate that accesses are permitted, to levels indicating that accesses are not permitted.