Semiconductor memory device and refreshing method of semiconductor memory device

A semiconductor memory device comprising:

• a memory array which includes a plurality of memory blocks;
• an address allocation information storage unit which stores address allocation information which is address information allocated to the memory blocks;
• a block selection circuit which selects one memory block which corresponds to an input address which is input on the basis of the address allocation information;
• and
• a refresh control circuit which controls a refreshing operation of the memory array,
• wherein one of the memory blocks is allotted to a surplus memory block, and
• wherein when a refresh command is supplied, the refresh control circuit
• transfers data which is stored in one memory block which is a refreshing object in the memory blocks to the surplus memory block and
• after completion of data transfer to the surplus memory block, allocates the address information of the memory block which was the refreshing object to the surplus memory block to which the data is transferred and newly allots the memory block which was the refreshing object to the surplus memory block.