A memory storage apparatus including a connector, a rewritable non-volatile memory module and a memory controller is provided. The memory controller receives a password to be verified, transforms the password into a data stream by using a first unit, generates a cipher text to be verified according to a predetermined data stream and the transformed data stream by using a second unit, and determines whether the cipher text to be verified is the same to a predetermined cipher text stored in the rewritable non-volatile memory module. When the cipher text to be verified is the same to the predetermined cipher text, the memory controller identifies that the password to be verified is validated. Accordingly, the memory storage apparatus can effectively verify a password input by a user, thereby protecting data stored in the rewritable non-volatile memory module.