An flash memory erase method. A bias Vg is applied to a gate of a memory cell. A bias Vd is applied to a source/drain region of the memory cell to execute an erase operation. The bias Vd is increased from an initial value to a predetermined value over time. During the increase of the bias Vd, no inspection is performed. Whether the memory of each memory cell has been erased is inspected. If the erase operation is complete, the erase operation is over. If not, a voltage raise erase-inspection step is performed at least once until it is confirmed that the memory of all the memory cells has been erase. Each voltage raise erase-inspection step includes an erase step with a raised voltage and an inspection step afterwards.