PURPOSE: To easily prevent the attenuation of an amplitude of a ultrahigh frequency clock signal on a printed circuit board.

CONSTITUTION: Plural clock signal transmission lines 2, 4 whose surge impedance differs are connected in series on an insulation board 3, a supply source 1 for an original clock signal is provided in a direction that amplification due to mismatching of positive reflection wave is implemented at adjacent connecting points of the signal transmission lines, a larger amplitude clock signal than the amplitude of the original clock signal is obtained at the signal transmission line, the clock signal after amplification is extracted from the signal transmission line to be used for the clock signal for an integrated circuit.