A semiconductor memory device capable of automatically restoring writing interrupted due to a momentary stop or a fluctuation of a power supply voltage is provided. A non-volatile memory of the disclosure includes a memory cell array formed with a NOR array and a variable resistance array. When the power supply voltage drops to a power-off level during writing into the NOR array, a reading/writing control unit writes unwritten data into the variable resistance array. Subsequently, when a power-on of the power supply voltage is detected, the reading/writing control unit reads the unwritten data from the variable resistance array and writes the unwritten data into the NOR array, so that interrupted writing is restored.