A suboptimal control theory is adopted to maximize the performance of an active turbulence control in the fully developed channel flow. The control input is a virtual body force field, which damps the spanwise velocity fluctuations within a thin layer adjacent to the wall. The method used is to minimize a cost functional, which is constructed so as to represent a balance of the square body force strength and the square spanwise velocity gradient , the latter represents the dominant compo-nent of either the streamwise vorticity or the strain rate. From a series of direct numerical simulations, it is found that the suboptimal control achieves a turbulent drag reduction as large as that obtained by an unoptimized active control, but the work required for control is to be estimated much smaller.