PURPOSE: To restrain mutual interference in electromagnetic radiation and to improve the movability of a test head by using an optical fiber cable for transmitting a signal and performing spectral multiplex transmission by a small number of optical transmission lines.

CONSTITUTION: A CPU 11 previously transmits code data corresponding to transmitted contents to a switching circuit 13 through a data bus 12. The circuit 13 performs the switching action based on the code data and a light emission source 14 allows light emitting bodies 141 - 14n to emit light corresponding to the action. A luminous flux L passes through an optical fiber 15 and reaches a spectral analyzer 16 so as to be spectrally splitted. The spectrum is converted into an electric trigger signal by a spectral/electric conversion circuit 17. By utilizing the trigger, a pattern generator 18 reconstitutes a waveform for an IC test and a relay matrix control part 20 controls the opening and closing of a relay matrix, then an input/output signal adjusting part 19 adjusts the level of the waveform. The adjusted signal is the input for an IC 4 to be mea sured.