The purpose of this study is to investigate and propose a vibration isolation system with a negative stiffness structure (NSS) for driver seats in low frequency vibration conditions. In this paper, the nonlinear stiffness characteristic of the system is presented. The relationship between the configurative parameters and the stiffness of the elastic element, for which the dimensionless nonlinear stiffness of the proposed system ranges from zero to one and the range of the displacement of the isolation equipment (mass) is the maximum without exceeding a desired value of stiffness, will be obtained. An experimental apparatus is subsequently configured to examine the characteristic of the vibration transmissibility of the system according to various values of the configurative parameters. Next, the time responses to the multiple frequency and random base excitations are also investigated. In addition, the dynamic responses of the system with and without the negative stiffness structure are considered. The results show that the proposed system has a wide frequency range of isolation, especially since the resonance phenomenon almost does not occur. ► A vibration isolation system using negative stiffness structure (NSS) for vehicle seat is presented. ► Nonlinear stiffness characteristics of this NSS is clearly explained. ► Time responses with respect to multi frequency and random base excitations are also investigated. ► The isolation performance by the proposed system was verified to be very effective.