In a dynamic burn-in apparatus wherein a signal output from a signal generator is input to a semiconductor device to be tested in the burn-in tank, a converter is arranged at the output of the signal generator. The converter increases, by N times, the frequency of the signal output from a signal generator. The signal having the increased frequency and output from the converter, is input to the semiconductor device to be tested in the burn-in tank when the burn-in is operated at high-speed. The frequency of the signal is converted to the higher frequency, and the signal having the higher frequency is provided to the semiconductor device. As the result, the burn-in can be done in a shorter time for a high-speed sophisticated semiconductor device.