PURPOSE: To make the adoption of a folded bit line system possible by connecting respectively a word line and a bit line, a word line and an anti-bit line to a memory cell and adjusting potentials of a bit line and an anti-bit line at the time of reading as required in a differential type sense system.

CONSTITUTION: In the differential type sense system to which a bit line BL and anti-bit line BL- are connected in parallel, memory cells MC1, MC2 are respectively connected to a word line WL and a bit line BL, a word line and an anti-bit line BL-. When potentials of the bit line BL and the anti-bit line BL- being the same potential at the time of pre-charge are set so as to have a difference between them, the memory cell MC1 or the MC2 is read out, a folded bit line system can be adopted, and reading operation and the like can be performed at high speed.