A semiconductor integrated circuit device includes a semiconductor substrate, an element isolation region, a first interconnection, a second interconnection, and a memory cell unit connected between a corresponding one of the first interconnection and a second interconnection. The memory cell unit includes two selection transistors and memory cell transistors of not larger than two. The memory cell transistors are connected between the two selection transistors. The memory cell transistor has a charge storage layer whose side surface lies in the same plane or in substantially the same plane as the side surface of the element isolation regions.