A method is provided for refreshing a volatile memory. The method includes storing address information about a weak cell row address that is to be refreshed according to a weak cell refresh period that is shorter than a refresh period, performing a counting operation for generating a refresh row address, comparing the refresh row address with the address information, refreshing the weak cell row address when a result of the comparison shows that the refresh row address and the weak cell row address of the address information coincide with each other, changing the weak cell row address by changing a pointer of the address information, and refreshing the changed weak cell row address according to the weak cell refresh period.