A wear compensation device of a clutch actuator may include a screw movable along a longitudinal direction of a pull-rod axially received in the screw, a screw guider holding the screw to allow movement in the longitudinal direction and having a connection pin connected to a link member, a compensation nut supported by the screw guider, engaged with the screw, and having catching teeth, a compensation ring externally coupled with the compensation nut, having a catching protrusion to be locked with the catching teeth in one direction thereof, and having a guide pin on an external circumference of the compensation ring, and a guide block fixed to a housing, having a guide groove to receive the guide pin, and guiding the guide pin to rotate the compensation ring when the pull-rod is operated to a wear compensation range.