A circuit which can reduce time taken by a clock alignment training operation in a semiconductor memory device is provided. The semiconductor memory device, which includes: a clock inputting unit configured to receive a system clock and a data clock; a clock dividing unit configured to divide a frequency of the data clock to generate a data division clock, wherein the clock dividing unit determines a phase of the data division clock in response to an inversion division control signal; a phase dividing unit configured to generate a plurality of multiple phase data division clocks having respective predetermined phase differences in response to the data division clock; a data serializing unit configured to serialize predetermined parallel pattern data in correspondence with the multiple phase data division clocks; and a signal transmitting unit configured to transmit an output signal of the data serializing unit to the outside.