A semiconductor integrated circuit device includes an nonvolatile semiconductor memory cell and a write control circuit. The write control circuit supplies first and second pre-programming pulses and staircase programming pulses to the memory cell independently of the write statuses thereof. The second pre-programming pulse is higher than the first pre-programming pulse by a first potential difference. The staircase programming pulses have an initial voltage lower than the second pre-programming pulse and increase the voltage at a rate of a second potential difference per pulse. The second potential difference is smaller than the first potential difference.