According to the invention, mounting area is decreased and yield is improved by decreasing the number of elements, and a memory with less burden on peripheral circuitry and a driving method thereof are provided. The invention comprises a memory cell including a memory element in a region where a bit line and a word line cross with an insulator interposed between them, a column decoder, and a selector including a clocked inverter. An input node of the clocked inverter is connected to the bit line while an output node is connected to a data line. Among a plurality of transistors connected in series which form the clocked inverter, a gate of a P-type transistor of which source or drain is connected to a power source on the high potential side VDD and a gate of an N-type transistor of which source or drain is connected to a power source on the low potential side VSS are connected to the column decoder.