A memory system includes a memory device and a memory controller. The memory device includes a memory area configured to store data and an input/output (I/O) buffering part configured to store data outputted from the memory area. The memory controller is configured to control read operations of the memory device. The memory device is configured to store data of all columns in a selected row designated by a row address among a plurality of rows in the memory area into the I/O buffering part in response to an external command outputted from the memory controller and is configured to output data of a selected column designated by a column address among the data stored in the I/O buffering part, and the memory controller is configured to perform a scheduling operation for successively executing read request commands having the same row address among a plurality of read request commands for performing read operations of the memory device.