A common memory device shared by a first processor and a second processor is provided. The common memory device includes a memory cell array including a first memory region allocated for the first processor and a second memory region allocated for the second processor, a refresh masking information storage circuit configured to store refresh masking information indicating whether a refresh is performed on at least one of the first and second memory regions, and a refresh circuit configured to selectively perform the refresh on the first memory region and the second memory region according to the refresh masking information.