Abstract: An electrically erasable and programmable read only memory device executes a verifying operation on a selected memory cell after a programming operation, and a predetermined voltage higher than a read-out voltage is applied to the control gate electrode to see whether or not the threshold level of the selected memory cell is high enough to remain in the programmed state, wherein the predetermined voltage is internally produced from an external power voltage level so that an electronic system is not expected to be equipped with a source of predetermined voltage, thereby making the electronic system simple.