<p>This paper presents the under actuated robot which have adaptive motion and hard stiffness by wire drive and jamming transition phenomenon. This robot hand have the fingers which can change the posture passively by wire drive. The fingers are connected to an actuator through elasticity elements. Therefore all fingers can change theirs posture passively along object shape by driving the actuator. After fingers motion, the density of granular body in the fingers increases by sucking air in the fingers. Jamming transition caused, and the fingers have hard stiffness. The robot hand can grasp wide range objects by this process.</p>