In recent years, various seismic isolators have been developed to prevent earthquake damage to valuable art and other rare objects. In this study, we developed a vertical seismic isolator that can support loads using a slanting spring without requiring a vertical spring. The experimental value of the natural frequency was 0.45 Hz. We proposed the dynamic model and the theoretical values of the frequency characteristics were close to the experimental values. In addition, we verified this vertical seismic isolator’s performance through shaking tests and simulation for typical seismic waves in Japan. The average reduction rate of the acceleration was 0.26.