A synchronous semiconductor memory device includes a data alignment reference pulse generation unit configured to generate a data alignment reference pulse in response to a data strobe signal, a data alignment suspension signal generation unit configured to generate a data alignment suspension signal in response to the data alignment reference pulse, a data strobe termination signal, and a write pulse, and a data alignment unit configured to align input data in response to the data alignment reference pulse and stop aligning the input data in response to the data alignment suspension signal.