Abstract: A data protection method and device by using address. A memory device is used to establish a database that comprises a usage authorization when the address of the data is used to distinguish the usage authorization when a user accesses the data as well as the password that is needed for the authentication to release the usage authorization. An address decoder is used to determine whether the access of the data exceeds the data usage authorization when user accesses the data. If it does, notifying the user to input an authentication password. If it does not, the data can be directly accessed and used by the user. Further comparing the authentication password input by the user with the password that is stored in the database inside the memory device. If they match each other, the data usage authorization is released and the user can access and use the data. If they do not match, then the user is restricted to use the data within the usage authorization.