Attempts have been made to control the spontaneous random motion of a tetrahydrofuran-swollen amphiphilic polymer gel on a water surface. By allowing the ejection of tetrahydrofuran through spouting holes, the gel showed an improved translational motion with a velocity of 77 mm/s or rotation with a rotation rate of 394 rpm. The controlled rotation showed an energy efficiency of 4.5×10-3%, which was 10 times of that of random motion. On the basis of the improved rotational motion of the gel, a generator consisting of a gel rotor equipped with a pair of permanent magnets and a solenoid coil has been constructed. The generator rotor which was 40 mm long, 6 mm wide, and 2 mm thick, produced an alternative electric power with an instantaneous electromotive force as high as 15 mV for a period of over 30 min. Such behaviors as the controlled motion, the spreading rate of tetrahydrofuran on the water surface, the crystallization and texture of gel surfaces, and the power generated have been described.