Remarkable progress in the miniaturization of multilayer ceramic chip capacitors has been made in recent years. When using the chip capacitor as a signal coupling capacitance, improvement in the high frequency characteristics is expected due to downsizing of the chip capacitor. According to the conventional equivalent circuit model, the lower limit of the coupling bandwidth is determined by the capacitance while the higher limit is affected by the parasitic inductance associated with the chip structure. In this study, we investigate the coupling characteristics up to millimeter wave frequencies by the measurement and simulations. As a result, a new equivalent circuit model of the chip capacitor is proposed presuming a change in the current distribution within the chip structure.