Provided is a storage apparatus capable of encrypting data without affecting the business performance. This storage apparatus includes a cache memory, a first controller for controlling the writing of data in the cache memory pursuant to the write command, a second controller for controlling the writing of the data written in the cache into the storage devices, and an encryption engine for encrypting data pursuant to the write command. When the second controller reads the data from the cache memory and writes the data in said storage devices, the encryption engine encrypts the data, and the second controller writes the encrypted data in said storage devices.