Source lines for a spin injection magnetic memory cell are arranged parallel to word lines for executing writing/reading of data multiple bits at a time. In a write operation, a source line potential changes in a predetermined sequence such that the source line commonly connected to a plurality of selected memory cells is set to pass a current only in one direction in each stage of the operation sequence. For the data write sequence, a current is caused to flow through memory cells according to write data sequentially, or the memory cell has a resistance state set to an initial resistance state before writing, and then changed to a state according to the write data Fast writing can be achieved in the magnetic memory without increasing a memory cell layout area.