We have developed a novel “self-oscillating” gel that exhibits an autonomous mechanical oscillation without any external stimuli. Here the ternary self-oscillating polymer composed of N-isopropylacrylamide and N-(3-aminopropyl)methacrylamide and Ru(bpy)3 was newly synthesized by atom transfer radical polymerization (ATRP) and the gel was prepared. For the self-oscillating polymers and gels with various compositions, their phase transition and self-oscillating behaviors were investigated considering the potential for biomedical application. It was demonstrated that the swelling–deswelling behavior of the self-oscillating gels can be controlled by changing the composition ratio of the free amino group present in the polymer and the conjugated Ru(bpy)3 moieties. Therefore the hydrophilic/hydrophobic balance is controllable and adjustable by this composition ratio.