A data storage device includes a memory block, a data classification unit, and a memory control unit. The memory block includes a high-speed nonvolatile memory and a low-speed nonvolatile memory, wherein a data access speed of the high-speed nonvolatile memory is greater than a data access speed of the low-speed nonvolatile memory. The data classification unit classifies the externally input data into data groups including busy data and free data, where the busy data has greater access frequency than the free data. The memory control unit configured to store the externally input data classified by the data classification unit as busy data in the high-speed nonvolatile memory, and to store the externally input data classified by the data classification unit as free data in the low-speed nonvolatile memory.