A memory controller to control a memory device includes an Error Checking and Correcting (ECC) engine to perform error detection on data read from the memory device and a data operation manager. The data operation manager is to control a first rewrite operation of the memory device on selected memory cells to compensate for a drift in a distribution of the selected memory cells, based on a result of a test read operation of the memory device on test cells, determine a distribution adjustment degree based on a result of a normal read operation, as an ECC decoding operation corresponding to the normal read operation of the memory device is successfully performed by using the ECC engine, and control a second rewrite operation of the memory device based on the determined distribution adjustment degree.