A data storage device includes a nonvolatile memory device and a controller including a command parser configured to match a clock corresponding to each of a plurality of memory access types to generate a clock index matched with each of the memory access types and configured to determine, when a command is received, a memory access type of the command and the clock index matched with the determined memory access type by analyzing the command, and a memory interface configured to determine a locking value and the clock index corresponding to each of a plurality of clocks having different frequencies and change the locking value for processing of a command according to the clock index determined by the command parser.