Write driver of semiconductor memory device and operation method thereof

A write driver of a semiconductor memory device and an operation method thereof are provided to perform stable and reliable operation as reducing the load of a core voltage during write operation of the write driver. A pullup/pulldown driving unit(200) performs pullup/pulldown driving of a second data line according to data loaded on a first data line. A pulse generation unit(240) generates a pullup over driving pulse enabled as much as expected time at the initial stage of a pullup period of the second data line. An over driving unit(260) performs pullup driving of the second data line with an over driving voltage higher than a pullup voltage of the pullup/pulldown driving unit in response to the pullup over driving pulse.