In this study, integration control of air-cell seat and semi-active suspension is proposed to minimize the road-tyre force which can cause uncomfortable feeling to rider. The proposed integration control with sliding perturbation observer is consisted of air-cell seat control which uses the force generated by air-cell and the sky-hook control. The air-cell seat itself has been modeled as a 1 degree of freedom spring-damper system. The actual characteristics of the air-cell have been analyzed through experiments. In this paper, we introduces a new robust motion control algorithm using partial state feedback for a nonlinear system with modelling uncertainties and external disturbances. The major contribution of this work is the development and design of robust observer for the state and the perturbation. The combination skyhook controller and air-cell controller using the observer improves control performance, because of the robust routine called Sliding Observer Design for Integration Control of Air-Cell Seat and Semi-active Suspension. The simulation results show a high accuracy and a good performance.