A method for operating a memory device is disclosed. The method includes receiving a serial data and a serial cyclic redundancy check (CRC) code transmitted sequentially through a channel, converting the serial data into a parallel data and the serial CRC code into a parallel CRC code, outputting the parallel data at a first time point, outputting the parallel CRC code at a second time point later than the first time point, calculating a CRC code by using the parallel data, comparing the parallel CRC code and the calculated CRC code with each other and detecting an error of the serial data transmitted through the channel according to the result of the comparison, and outputting an error detection signal in response to the result of the comparison.