A semiconductor memory device having a floating body capacitor. The semiconductor memory device can perform a memory operation using the floating body capacitor. The semiconductor memory device includes an SOI substrate having a staked structure in which a base substrate having a conducting surface, a buried insulating layer and a device-forming layer are staked, a transistor formed in a portion of the device-forming layer, having a gate, a source region and a drain region, and a capacitor formed by the buried insulating layer, the conducting surface of the base substrate, and accumulated holes generated in the device-forming layer when the transistor is driven.