A new design method for regulator problems for singularly perturbed systems is proposed in this paper. In contrast to previous papers using the Riccati equation approach and composite controls, a direct control without any Riccati equation is presented. It is applicable to solving a regulator problem for time-invariant and time-varying systems with unconstrained controls as well as with constrained controls. The approach is based on a version of the Tikhonov theorem in L(2) for solutions of singularly perturbed systems to be proved in the paper and some techniques of sensitivity analysis for optimization with strictly convex objective functions.