A flash memory device has improved erasable characteristics and device reliability. The flash memory device includes a semiconductor substrate and heavily doped impurity regions formed spaced apart from one another by a predetermined distance in the semiconductor substrate in a first direction. First and second isolation regions are formed spaced apart from each other by a second predetermined distance on the semiconductor substrate, in a second direction which is preferably at a right angle to the first direction. Each of the floating gates are formed between the first and second isolation regons and between the heavily doped impurity regions. The control gate lines are formed between the first and second isolation regions, and over the floating gates in the same direction as the first and second isolation regions. An erase gate line is formed to have a narrower width than the floating gate, and is formed over the floating gate, preferably at a right angle to the control gate line.