Engineering Test Satellite VI (ETS-VI) is a three-axis-stabilized satellite launched by NASDA in 1994. The FLEX experiments which consist of identification and attitude control experiments on orbit were planned as one of the ETS-VI on-board experimental programs and carried out in 1995. The purpose of the FLEX experiments was to establish fundamental attitude controller design methods for a flexible-structure satellite. In this paper, some results of the attitude control experiments are presented. The attitude controllers were designed using H_∞ control method and two-degree-of-freedom control method. At that time, as the program memory area for the FLEX experiments was limited to about 2.6 Kbytes, the feedforward control design methods which never increase the order of the controller were adopted in this paper. Experimental results showed high control performance which was expected by simulation results on the ground. Noting that the on-orbit experiments presented have never been carried out, we believe these results will be utilized for attitude controller design in the future.