A semiactive damper has a controllable damping force as an advantage point, but it necessarily has a time delay at mechanically switching by a control. Therefore, a control law does not work perfectly enough, a command signal is saturated at upper limit, and performance is depended on the time delay. If the damping force can be switched as quickly as possible, it will be comparatively more effective and useful for vibration reduction under quick motion such as earthquakes which has a high frequency domain. In this paper the authors propose a radically different approach way how to mechanically improve the time delay at switching for a semiactive damper under control. In order to switch more quickly, the command signal to the damper using a parametric excitation is demonstrated. Rising time of a test mechatronic damper which can switch the damping force by controlling external resistance of a generator are measured when it is periodically subjected to a triangle wave. The experimental results are compared with conventional system using a step function or an overshot impulse function. Finally, improvement of a time delay using parametric excitation is confirmed experimentally.