A semiconductor storage device includes a memory cell, a switch, a source driver, a drain driver, a voltage measurement circuit and a control electrode driver. The memory cell has a control electrode, a floating electrode, a source and a drain. In a writing to the memory cell, the voltage measurement circuit measures a voltage generated between the control electrode and the source when the switch is in an on state connecting the control electrode and the drain and a predetermined current flows from the current source to the memory cell, and the control electrode driver applies to the control electrode a voltage that is controlled based on the voltage measured by the voltage measurement circuit.