To provide an actuator for feeding a linear material capable of dispensing with a special treatment on a linear material and the addition of accessories and positively moving the solid linear material in its extending direction.

This actuator 10 for expanding a rod antenna is provided with a fixed element 11 fixed to a rib 1a of a portable telephone case 1, and having a grip part HR on its free end side in a state of being penetrated through an extensible pipe 2d to be abutted on and separated from its peripheral face, a first piezoelectric element 12 for gripping increasing the decreasing the gripping force of the grip part HR, a piezoelectric element 13 for stepping, fixed to the fixed element 11 at its one end, and expanded and contracted in the extending direction of the extensible pipe 2d, a movable element 14 partially fixed to the other end of the piezoelectric element for stepping 13 and having a grip part HL on its free end side in a state of being penetrated through the extensible pipe 2d to be abutted on and separated from its peripheral face, and a second piezoelectric element 15 for gripping increasing and decreasing the gripping force of the grip part HL.