This paper presents a new design of an artificial muscle actuator called tube-spring actuator (TSA) that is fabricated with dielectric elastomer. The new actuator construction includes two steps: the first is that a cylindrical actuator is manufactured with dielectric elastomer with multi-layer lamination process. Then a compressed spring is inserted to inside the tube as the second step of the process. The inner spring is used to maximize the axial deformation while constraining the radial contraction. This design enables effective linear actuation with largest amount strain. The monitored strain of active length is up to 15 percents. The manufactured actuator is applied to a robot hand as an example of the actual application.