According to one embodiment, a testing device includes a signal generator that generates a first signal output to a device under test, a channel selector provided after the signal generator and configured to select one of a plurality of channels, a signal receiver that receives the second signal supplied from the device under test, a correction value calculator that calculates a correction value for calibrating loss of a respective one of the channels, wherein the correction value calculator calculates a correction value for calibrating loss of a respective one of the channels included in the channel selector, based on a signal level received by the signal receiver via a loopback channel, when a calibration-level output state indicating a state where a signal level of the first signal generated by the signal generator reaches a predetermined transmission reference level of calibration is assumed.
