An array test apparatus includes a signal transmission unit which transmits a data signal to each of a plurality of data lines of a low-temperature polysilicon (“LTPS”) substrate, a signal measurement unit which measures the data signal of each of the data lines of the LTPS substrate, a timer which generates a horizontal period for setting a section in which the data signal is transmitted from the signal transmission unit to each of the data lines and a section in which the data signal output from each of the data lines is measured by the signal measurement unit, and a determination unit which determines whether each of the data lines of the LTPS substrate is normal based on the data signal measured by the signal measurement unit.