In the data input apparatus, a data delay unit outputs data input from outside the data input apparatice. The data delay unit varies the degree of delay in response to a test mode signal. A data alignment signal generating unit receives a first signal synchronized with an external clock signal and a second signal synchronized with a data strobe signal, and the data alignment signal generating unit outputs one of the first signal and the second signal as a data alignment signal in response to the test mode signal. A data alignment unit is synchronized with the data alignment signal to align the data delayed in the data delay unit. The data input apparatus improves the setup/hold window when a semiconductor memory device is in the test mode.