A control apparatus is applied to a hybrid vehicle. The hybrid vehicle includes an internal combustion engine and a second MG as driving sources, and a power split mechanism which is capable of changing and transmitting to an output portion transmitting torque to drive wheel, a rotating speed of the internal combustion engine. And, the hybrid vehicle is capable of switching a gear ratio mode of the power split mechanism between a variable gear ratio mode and a fixed gear ratio mode.The control apparatus determines whether or not a switching of the gear ratio modes is prohibited based on a vehicle speed and a gradient of a road. And, when it is determined that the switching is prohibited, the control apparatus maintains the gear ratio mode in the variable gear ratio mode or the fixed gear ratio mode.