A data updating method, a memory system and a memory device in which the memory device is connectable to a host device and has a memory section and a memory controller, the memory section consists of a first memory section which can be divided into partitions having multiple different attributes, and a work space which is managed by the memory controller, and the method of updating data which is stored in the memory device uses one of the writing methods which has been selected from among multiple different writing methods of writing data into the partition, depending on the attribute of the partition, to perform an updating process, and can securely update the data.