A method for performing an erase operation in a memory cell. A first voltage and a second voltage are applied to the source and drain regions, respectively, for a predetermined erase time; and the first and second voltages are switched with each other between the source and drain regions at least one time for the erase time. Thereby, hole is easily injected to the source and drain regions and a channel lateral surface, and a uniform and high-speed erase operation is archived.