A resistive memory and a method for writing data thereof are provided. The method for writing data includes: receiving a write-in data and generating an inverted write-in data; reading a current data in a plurality of selected memory cells; comparing the current data with the write-in data and the inverted write-in data; selecting the write-in data or the inverted write-in data to generate a final data according to a comparison result; and writing the final data into the selected memory cells.