An electrically writable nonvolatile semiconductor memory device capable of writing data to any desired threshold value accurately without resorting to a write confirming operation is disclosed. The memory device senses a current flowing through a memory cell transistor while effecting a writing operation. When the current reaches a preselected value, the memory device stops the writing operation. A relation between a desired threshold voltage and the current to flow through the memory cell transistor during wiring is determined beforehand. This eliminates the need for the confirmation of the threshold voltage relying on a reading operation, and allows a desired threshold voltage to be set rapidly and accurately.