A method of writing data in a resistive memory device having a memory cell array divided into first and second tiles includes; performing a first simultaneous write operation by performing a set write operation performed on resistive memory cells of the first tile while simultaneously performing a reset write operation on resistive memory cells of the second tile in response to the write command, and performing a second simultaneous write operation by performing a reset write operation on resistive memory cells of the first tile while simultaneously performing a set write operation on resistive memory cells of the second tile in response to the write command.