Thin film magnetic memory device capable of conducting stable data read and write operations

A thin film magnetic memory device, comprising:

• a plurality of magnetic memory cells for retaining storage data written by an applied magnetic field;
• and
• a dummy memory cell for generating a read reference voltage in data read operation, wherein
• each of said magnetic memory cells and said dummy memory cell include
• a magnetic storage portion having either a first electric resistance value or a second electric resistance value that is higher than said first electric resistance value depending on a level of said storage data, and
• an access gate connected in series with said magnetic storage portion, and selectively turned ON, said thin film magnetic memory device further comprising:
• a first data line that is electrically coupled to a magnetic memory cell selected from said plurality of magnetic memory cells in data read operation so that a data read current is supplied to said first data line;
• a second data line that is electrically coupled to said dummy memory cell in data read operation so that a data read current equal to that of said first data line is supplied to said second data line;
• a data read circuit for producing read data based on respective voltages on said first and second data lines;
• and
• a resistance adding circuit for adding a third electric resistance in series with said first data line, said third electric resistance being smaller than a difference between said first and second electric resistance values, wherein
• said magnetic storage portion in said dummy memory cell stores a data level corresponding to said second electric resistance value.