Provided is a control system (1) for a hybrid vehicle (8) which is configured to directly transmit an output of an internal combustion engine (2) to a driven wheel (17) via a lockup clutch (18) and transmit an output of an electric motor is to the driven wheel by disengaging the lockup clutch depending on an operating state of the vehicle. The control system is configured to activate a warning unit (36, 37) when the oil pressure is below a prescribed oil pressure threshold value and the rotational speed of the engine detected by the rotary encoder is higher than a rotational speed threshold value. The rotational speed threshold value is a first threshold value when the lockup clutch is fully disengaged, and a second threshold value higher than the first threshold value when the lockup clutch is fully engaged, being engaged and being disengaged.