A test device includes: a testing unit connected with a measurement line, and configured to apply bias to the measurement line and measure the measurement line; a plurality of switching units configured to electrically connect the measurement line and the plurality of samples; and a control unit configured to sequentially turn on the plurality of switching units to sequentially apply the bias to the plurality of samples. The control unit determines whether a corresponding device sample has a defect based on a first measurement value according to measurement by the testing unit when the bias is applied to each of the plurality of samples.