PURPOSE: To keep the non-conductive state of a parasitic transistor under a field oxide film positively, and to prevent the interference of informations between adjacent storage capacitance by applying negative potential to a polycrystalline silicon film as a first electrode for storage capacitance.

CONSTITUTION: The negative potential of a power supply 14 is connected to a polycrystalline silicon film 9 as a first electrode 2 for storage capacitance 1. Consequently, a small number of carriers under a field oxide film 12 between adjacent storage capacitance 1 and 1a are removed by applying negative potential to the polycrystalline silicon film 9 on the field oxide film 12, a large number of carriers are induced, and possibility of which a channel for a parasitic transistor is converted into an N type and brought to a conductive state can be prevented. Accordingly, a dRAM having excellent charge holding characteristics of storage capacitance and high reliability can be obtained easily.