A memory device may determine cell count information from a threshold voltage distribution of memory cells and may determine a detection case based on the cell count information when an error in read data, received from the memory device performing a read operation is not corrected. A memory controller may control the memory device to execute a read operation using a development time determined in consideration of an offset voltage of a read voltage corresponding to the detection case. When an error in the read data is successfully corrected, the memory controller may update a table, stored in the memory controller, using a dynamic offset voltage obtained by inputting the cell count information to a machine learning model.