Piezoelectric shunt damping is a technique for vibration suppression by connecting an external circuit called the shunt circuit to a piezoelectric element attached to a mechanical structure. Many previous studies consider only a single mode for designing shunt circuits. However, the vibration structures typically include multiple vibration modes. This paper inspects the gap between the design for the single mode system and implementation for the multimode systems. The Negative Capacitor (NC)-circuit, which consists of a negative capacitor and a resistor is tested. Then, we have found that the spillover phenomenon occurs on the lower frequency side in the multimode piezoelectric NC-shunt damping in the previous research. In this paper, we have analyzed the lower frequency side spillover phenomenon.