The polarity of polymer-actin complexes obtained by mixing F-actin with synthetic polymers carrying positive charges such as poly(L-lysine), x,y-ionene bromide polymers, and poly(N-[3-(dimethylamino)propyl]acrylamide) (PDMAPAA-Q) have been investigated. Actin complexes formed with poly(L-lysine) and PDMAPAA-Q, which carry charges on their side chains, show a higher polarity than those formed with x,y-ionene bromide polymers, which have charges on their chain backbones. All these polymer-actin complex gels show motility on the surfaces coated with myosin by coupling to adenosine 5'-triphosphate hydrolysis. A linear correlation between the polarity of polymer-actin complex gels and the motility is observed.