A data processing apparatus includes a non-volatile semiconductor memory configured to store a storage data and an additional data control circuit configured to generate an additional data and add the additional data to a main storage data, and the additional data is different between a first mode and a second mode. The additional data control circuit includes a first mode circuit configured to generate the additional data in the first mode; and a second mode circuit configured to generate the additional data in the second mode. The storage data contains a target data or an inversion data of the target data, as the main storage data and the additional data.