A storage device including: a memory controller configured to output user data received from outside of the storage device in a write operation mode and receive read data in a read operation mode; and a memory device including a memory cell array and a random input and output (I/O) engine, the random I/O engine configured to encode the user data provided from the memory controller using a random I/O code, in the write operation mode, and to generate the read data by decoding internal read data read by a data I/O circuit from the memory cell array using the random I/O code, in the read operation mode.