This study gives a method employing the state dependent Riccati equation for the control of nonlinear quarter vehicle active suspension system. Hydraulic actuator is used as force actuator in the quarter vehicle active suspension system and its dynamic behavior is nonlinear. Then, the nonlinear state equations written for the dynamics of the quarter vehicle model are rearranged in a state dependent coefficient form. After that, a cost function is written in order to minimize the sprung mass acceleration, suspension deflection, sprung mass velocity, tire deflection, unsprung mass velocity, pressure decrease through the piston, and rate of pressure decrease through the piston. Finally, control input is obtained as the state dependent Riccati equation variables and the state variables. Quarter vehicle suspension system model of a Ford Fiesta Mk2 is considered in numerical studies to show the efficiency of the technique.