Provided is a one-transistor (1T) floating-body DRAM cell device including a substrate; a gate stack which is formed on the substrate; a control electrode which is disposed on the substrate and of which some or entire portion is surrounded by the gate stack; a semiconductor layer which is formed on the gate stack; a source and a drain which are formed in the surface of the semiconductor layer and of which lower surfaces are not in contact with the gate stack; a gate insulating layer which is formed on the semiconductor layer; and a gate electrode which is formed on the gate insulating layer, wherein the remaining portion of the semiconductor layer excluding the source and the drain is configured as a floating body. The miniaturization characteristic and performance of a MOS-based DRAM cell device can be improved, and a memory capacity can be increased.