When writing into an antifuse memory element finishes, a value of resistance of the memory element rapidly decreases; accordingly, an output voltage of a boosting circuit which produces a writing voltage rapidly decreases. By detecting a change in the output voltage of the boosting circuit to control a writing command, the writing operation can be stopped immediately after the memory element is shorted. Thus, unnecessary current consumption caused by continuing a writing operation on the shorted memory element can be suppressed.