Optimal weighting matrix in LQR method for determining sliding surfaces is proposed for different types of sliding mode controllers (SMC). In order to identify the control performance variation of SMC accorcling to the dynamic characteristics of sliding surfaces, parametric study is performed for single-degree-of-freedom (SDOF) systems and control force limit is considered. Also, based on the results from SDOF systems，a procedure for optimal weighting matrix is proposed for multi-degree-of-freedom systems. Numerical analyses show that the SMC using proposed weighting matrix provide better control performance than the existing SMC, and it uses less control energy.