Nonvolatile storage device and method for writing into the same

A nonvolatile storage device comprising:

• a variable resistance element which includes a first electrode, a second electrode, and a variable resistance layer provided between said first electrode and said second electrode;
• a write circuit which writes data into said variable resistance element;
• and
• a read circuit which obtains resistance value data of said variable resistance element;
• wherein said variable resistance element has a property of changing from a first resistance state to a second resistance state when a pulse of a first voltage is applied to said variable resistance element, and changing from the second resistance state to the first resistance state when a pulse of a second voltage having a different polarity from a polarity of the first voltage is applied to said variable resistance element, the first resistance state being a state where first data is stored and the second resistance state being a state where second data is stored, and
• said write circuit performs additional writing on said variable resistance element based on the resistance value data obtained by said read circuit, after a writing operation for applying the pulse of the first or second voltage to said variable resistance element, and
• in the additional writing, when the pulse of the first voltage is applied to said variable resistance element in the writing operation, said write circuit applies, to said variable resistance element, at least a pulse of a third voltage and the pulse of the first voltage in this order, the third voltage having a smaller absolute value than an absolute value of the second voltage and a same polarity as the polarity of the second voltage.