Disclosed is an attenuation reduction structure for high-frequency connection pads of a circuit board with an insertion component. The circuit board includes at least one pair of differential mode signal lines formed thereon. A substrate has upper and lower surfaces respectively provided with at least one pair of upper connection pads and lower connection pads. A first metal layer is formed on the lower surface of the substrate. The first metal layer includes an attenuation reduction grounding pattern structure. The attenuation reduction grounding pattern structure includes a hollow area and at least one protruded portion. The protruded portion extends from the first metal layer in a direction toward the lower connection pads.