This paper proposes an approach to the provision of sliding mode control (SMC) with input constraint for engine idling-speed control. The aim of this experiment is to improve the stability of the system against disturbances such as fuel purges and torque loads. A steady-state error occurs because, in practice, the control input is restricted when an integral type SMC is employed to achieve stabilization. A modification to this approach is proposed that effectively uses compensation gain and variable switching gain. The compensation gain is derived from the control input difference, and the variable switching gain is described as an exponential function of the hyperplane. A mean-value engine model with dead time and disturbances is constructed in Matlab/Simulink. The simulation results show that the issue relating to steady-state deviation can be successfully solved with regard to disturbances having bias power; also, robustness is maintained during engine speed fluctuations. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.