A control system for a power transmission unit of a vehicle transmitting power outputted from a prime mover, comprising: a resonance detecting/predicting device for detecting or predicting a generation of a resonance of the power transmission unit resulting from a power transmission; a driving condition detecting device for detecting 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 for changing contents of 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.