A clutch actuating apparatus for a double clutch transmission, may include an electric unit that generates rotational force, a decelerating unit coupled to the electric unit and reducing the rotational force of the electric unit, a straight-converting unit that converts the rotational force reduced by the decelerating unit into a straight motion force, a push rod that is moved straight by the straight motion force of the straight-converting unit and makes an operational stroke to selectively engage a clutch, a supplement force supplying unit engaging with the push rod to increase the straight movement force to the push rod or to remove the increased straight movement force from the push rod when the push rod engages or disengages the clutch, and a rod locating unit coupled to the push rod and changing a relative position of the push rod to the straight-converting unit.