In the data read operation, a memory cell and a dummy memory cell are respectively coupled to two bit lines of a selected bit line pair, a data read current is supplied. In the selected memory cell column, a read gate drives the respective voltages on a read data bus pair, according to the respective voltages on the bit lines. A data read circuit amplifies the voltage difference between the read data buses so as to output read data. The use of the read gate enables the read data buses to be disconnected from a data read current path. As a result, respective voltage changes on the bit lines are rapidly produced, and therefore, the data read speed can be increased.