An attempt was made to prepare a biochemo-mechanical system that is capable of converting biochemical energy created as a result of an enzyme reaction into mechanical work through the swelling and shrinking of a gel. The preparation was performed via the physical entrapment of glucose oxidase (GOD) plus urease within an amphoteric polymer network. We used N-isopropylacrylamide (NIPA) as a main constituent of the network into which acrylic acid (AAc) as an anionic monomer and 1-vinylimidazole (VI) as an cationic monomer were introduced via radical polymerization. The gelation was carried out in the presence and the absence of the enzyme(s) by cross-linking with N,N'-methylenebisacrylamide of the monomer mixtures with molar ratios of NIPA/AAc/VI = 14:1:1 and 14:1.:2. The effects of pH and temperature on the swelling degree were studied in 50 mM NaCl solution. The ampholyte gels exhibited an isoelectric point (pI) at pH 5-6 at which the swelling degree reached a minimum value. Therefore, two pH regions bringing about gel swelling lie on either side of pI, that is, pH < 5 and pH > 6. This characteristic allowed the gel to undergo a shrinking-swelling oscillation passing through pi while an increase and a decrease in pH took place via the immobilized enzyme reactions within the gel phase. When the hydrolysis of urea with the immobilized urease raises the pH in the gel, it continues shrinking at pH < pI but swelling at pH > pI after attainment of an extremely collapsed state at pi. Such volume changes take place during a decrease in the pH because of the oxidation of glucose with the immobilized GOD. As a result, the shrinking-swelling oscillation was observed by alternative addition of the two substrates into the outer medium surrounding the gel.