A control system for a power transmission unit of a vehicle transmitting power outputted from a prime mover is disclosed. The control system includes a resonance detecting/predicting device which detects or predicts a generation of a resonance of the power transmission unit resulting from a power transmission; a driving condition detecting device which detects a driving condition of a vehicle in case the generation of a resonance is detected or predicted by the resonance detecting/predicting device; and a resonance dampening control selecting device which selects a control for dampening the detected or predicted resonance on the basis of the driving condition of the vehicle detected by the driving condition detecting device.