A semiconductor memory device includes a system clock input block configured to be inputted with a system clock, a data clock input block configured to be inputted with a data clock, a first phase detection block configured to compare a phase of the system clock, generate a first phase detection signal, and determine a logic level of a reverse control signal in response to the first phase detection signal, a second phase detection block configured to compare a phase of a clock acquired by delaying the system clock by a correction time, generate a second phase detection signal, and determine a logic level of a clock select signal in response to the first and second phase detection signals, and a clock select block configured to select and output the data clock or a clock acquired by delaying the data clock.