Disclosed herein is gear actuator for dual clutch transmission, including: a driving motor having a driving shaft formed with gear part, a pair of first and second gears gear-coupled to the gear part, first and second guide cams respectively connected to the first and second gears to rotate, a first power transfer unit transferring or cutting off the power from the driving motor to the first guide cam according to rotating direction of the first gear, a second power transfer unit transferring or cutting off the power from the driving motor to the second guide cam according to rotating direction of the second gear, a first finger shaft linearly moved by rotation of the first guide cam and performing a selection operation of an odd-numbered stage, and a second finger shaft linearly moved by rotation of the second guide cam and performing a selection operation of an even-numbered stage.