Provided is a method of refreshing a memory device by controlling a self-refresh cycle according to temperature. In the method, first self-refresh and second self-refresh are performed according to inner temperature of the memory device and a self-refresh cycle is controlled such that an all-bank-refresh (ABR) operation is not performed simultaneously with the start of the second self-refresh. The ABR operation is performed at the start of third self-refresh when the sum of a section of the first self-refresh in which the ABR operation is not performed and a section of the second self-refresh in which the ABR operation is not performed corresponds to a self-refresh cycle.