A triple clutch comprising: an input shaft which receives rotational power of an engine; a motor which includes a motor housing, a stator fixedly mounted on an outer circumferential surface of the motor housing, and a rotor rotatably disposed at a radially inner side of the stator; a clutch housing which is operatively connected to the rotor, receives rotational power of the motor while rotating together with the rotor, and has therein a clutch space; a first clutch which selectively transmits rotational power of the clutch housing to a first output shaft; a second clutch which selectively transmits the rotational power of the clutch housing to a second output shaft; and a third clutch which selectively transmits rotational power of the input shaft to the clutch housing, wherein all of the first, second, and third clutches (11, 12, 13) are disposed in the clutch space, an actuator (15A, 15B) which transmits axial force to the first clutch, the second clutch, or the third clutch, wherein the actuator (15A, 15B) comprises a first piston which transmits the axial force to the first clutch, a second piston which transmits the axial force to the second clutch, and a third piston which transmits the axial force to the third clutch, wherein the first piston and the second piston are provided in an actuator housing, and the third piston is mounted in a motor housing, wherein the first piston and the second piston are separated by a partition wall disposed between the first piston and the second piston, and an outer circumferential surface (D 2O) of the second piston is positioned to be closer to a radially outer side of a piston space in which the first piston and the second piston are mounted than an inner circumferential surface (D 1i) of the first piston, characterized in that the partition wall includes: a partition wall mounting portion which is mounted in the actuator housing, extends toward a front side, that is a side close to the input shaft, in the axial direction, and is slidably in contact with an outer end of the second piston; a partition wall connecting portion which extends radially inward from a front end of the partition wall mounting portion; and a partition wall extension portion which extends from an inner end of the partition wall connecting portion toward the front side in the axial direction and is slidably in contact with an inner circumferential surface of the first piston. a motor which includes a motor housing, a stator fixedly mounted on an outer circumferential surface of the motor housing, and a rotor rotatably disposed at a radially inner side of the stator; a clutch housing which is operatively connected to the rotor, receives rotational power of the motor while rotating together with the rotor, and has therein a clutch space; a first clutch which selectively transmits rotational power of the clutch housing to a first output shaft; a second clutch which selectively transmits the rotational power of the clutch housing to a second output shaft; and a third clutch which selectively transmits rotational power of the input shaft to the clutch housing, wherein all of the first, second, and third clutches (11, 12, 13) are disposed in the clutch space, an actuator (15A, 15B) which transmits axial force to the first clutch, the second clutch, or the third clutch, wherein the actuator (15A, 15B) comprises a first piston which transmits the axial force to the first clutch, a second piston which transmits the axial force to the second clutch, and a third piston which transmits the axial force to the third clutch, wherein the first piston and the second piston are provided in an actuator housing, and the third piston is mounted in a motor housing, wherein the first piston and the second piston are separated by a partition wall disposed between the first piston and the second piston, and an outer circumferential surface (D 2O) of the second piston is positioned to be closer to a radially outer side of a piston space in which the first piston and the second piston are mounted than an inner circumferential surface (D 1i) of the first piston, a partition wall mounting portion which is mounted in the actuator housing, extends toward a front side, that is a side close to the input shaft, in the axial direction, and is slidably in contact with an outer end of the second piston; a partition wall connecting portion which extends radially inward from a front end of the partition wall mounting portion; and a partition wall extension portion which extends from an inner end of the partition wall connecting portion toward the front side in the axial direction and is slidably in contact with an inner circumferential surface of the first piston.