This paper is concerned with the design of disturbance observer based optimal controller for an active control problem of a vehicle suspension system with saturated actuators against magnitude bounded disturbances. A quarter car model presented to analyze performance of proposed controller against bump road profile. Proposed control scheme composed of a disturbance observer and a control law with a state feedback and disturbance-feedforward. Gain matrices belong to disturbance observer and the control law are simultaneously computed to minimize L-2 gain of the closed loop system from disturbances to performance outputs by Linear Matrix Inequalities (LMIs) constraints. Finally, numerical simulations are carried out to demonstrate performance of proposed controller. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.