This paper presents a novel gripper capable of actively changing both shape and firmness. The gripper increases its grasp ability by changing its finger posture and firmness suitable for given target objects. In the proposed gripper, each finger is constructed by serially connecting multiple Juzu units. By controlling the angles between neighboring Juzu units individually using two actuators used for sending and bending, arbitrary finger shapes can be generated. In addition, by controlling the tension of the wire that penetrated all Juzu units in each finger, the friction between Juzu units is adjusted and the firmness of finger can be varied. A prototype gripper was designed and developed, and experiments to evaluate the capabilities of changing shape and firmness were conducted. Furthermore, through experiments of preshaping and grasping for various objects with different shape and size, the validity of the proposed method was demonstrated.