An erase method used in an array of flash memory cells arranged in a plurality of sectors provides each sector with an erase flag. The erase flag of sectors to be erased are set to a first value. The memory cells are sequentially verified from a first sector to a last sector whose flag is set to the first value and for each sector from a first address to a last address. When verification fails and the number of the same-cell-verifications is less than a predetermined number, the method applies an erase pulse and verifies the memory call at the same memory address again. When verification fails and the number of same-cell-verifications reaches the predetermined number, the remaining sectors whose flag is set to the first value are verified. When each memory cell of a sector to be erased passes verification, the erase flag of the sector is set to a second value. When the flag of each sector to be erased is set to the second value, the erase operation is terminated.