In this paper, design of a robust cascade controller for a Cuk converter is investigated. The controller contains two loop cascaded structure. The external voltage loop, which is the slow loop, contains the continuous proportional-integral(PI) voltage controller whereas the internal current loop, which is the fast loop, contains the continuous sliding mode controller(CSMC). The controller effectiveness is validated by simulating the Cuk converter in SimPowerSystems (R) toolbox of MATLAB/Simulink (R). The simulation is done for six different cases including ideal case, sudden variation of input supply voltage, load resistance, reference voltage, for noise disturbance and parametric variation. It is shown that the performance of the proposed controller is satisfactory and the ultimate goal of tracking the reference by the converter output voltage and the inductor current is achieved with little or no sensitivity to the uncertainties simulated.