Provided is a migration system considering security authentication levels and data protection strength levels of the both security devices between which data is migrated.A first terminal 102 includes a mechanism for protecting data by a private key in the public key method held by TPM, and a second terminal 103 includes a key in the private key method encrypted by the private key in the public key method held by TPM and a mechanism for protecting the data by the key. A Migration Authority 101 holds a security policy table describing a security policy and judges whether data movement from the first terminal 102 to the second terminal 103 is enabled according to the security policy table.