The influence of protein on friction of artificial cartilage material has been investigated to improve the friction and wear property. In this study the influence of secondary structure of adsorbed protein on friction was evaluated in a reciprocating friction tester. As a result, coefficient of friction depended on the ratio of content of β-sheet structure to that of random coil. It is supposed that the secondary structure of adsorbed protein is effective to control friction of PVA hydrogel.