Disclosed is a non-volatile memory device and a method of erasing the non-volatile memory device. An erase voltage is simultaneously applied to a plurality of sectors contained in the non-volatile memory device. Then, erase validation is sequentially performed for each of the plurality sectors and results of the erase validation are stored in a plurality of pass information registers. According to the results stored in the pass information registers, sectors which were not successfully erased are simultaneously re-erased and then sequentially re-validated until no such “failed sectors” remain in the non-volatile memory device. Upon eliminating the “failed sectors” from the non-volatile memory device, a post-program operation is sequentially performed on each of the plurality of sectors.