A clutch actuator includes: a reduction gear to rotate in a housing by a motor; a connecting rod having a first end connected to the reduction gear; a pair of levers provided on a hinge shaft in the housing, and connected to a second end of the connecting rod to rotate according to a rotation of the reduction gear; a push rod contacting with a clutch actuator fork; and a wear compensating unit movably coupled between the levers in a vertical direction and provided with an inclined surface contacting a first cam. In particular, the push rod has one end extended outwardly of the housing and is coupled with the first cam of which one end is movably inserted into the first hole of the levers.