A built-off test (BOT) device includes a signal processing block, an output selection block and a signal control block. The signal processing block duplicates a test signal to apply a plurality of duplicated test signals to each of a plurality of devices under test (DUTs) through each of corresponding channels, and the signal processing block provides a plurality of decision signals based upon a plurality of test result signals received from each of the DUTs. The output selection block merges the decision signals as a final decision signal or sequentially outputs the decision signals as the final decision signal, in response to an output mode selection signal. The signal control block provides the test signal to the signal processing block or provides the final decision signal externally, in response to a first switching control signal.