Non-volatile memory is an electronic memory device capable of maintaining information and performing fast data access without any additional power and having shockproof features. Therefore, non-volatile memory is extensively used in memory cards, solid state drives (SSD) and portable multimedia devices. When stored data has been read repeatedly, read disturbance of the non-volatile memory and incorrect storage of data may occur, and refresh of the non-volatile memory would become necessary at such point. However, frequent refresh may affect the lifetime of the non-volatile memory.