Patent ID: 6856537

Claim:
A thin film magnetic memory device, comprising: a plurality of memory cells holding magnetically-written stored data; wherein each of said memory cells includes a magneto-resistance element having one of a first electric resistance and a second electric resistance larger than said first electric resistance corresponding to said stored data; and each of said first and second electric resistances has a characteristic which changes corresponding to a voltage applied to opposite ends of said magneto-resistance element; said thin film magnetic memory device further comprising: a first data line connected to a first voltage and connected to a second voltage via a selected memory cell among said plurality of memory cells to receive a data read current on data reading; a dummy cell designed so as to have an intermediate electric resistance between said first and second electric resistances; a second data line connected to said first voltage and connected to said second voltage via said dummy cell to receive said data read current on said data reading; and a data read circuit generating read data based on a difference in passing currents between said first and second data lines; wherein said dummy cell includes a plurality of dummy magneto-resistance elements each having substantially the same characteristic as said magneto-resistance element; and each of said dummy magneto-resistance elements is connected to said second data line via another dummy magneto-resistance element connected in series, and a voltage applied to opposite ends of each said dummy magneto-resistance element is smaller than that applied to said magneto-resistance element on said data reading.