A control apparatus of a plug-in hybrid electric vehicle that is provided with a fuel tank, an engine, a battery, and an electric motor. The battery is chargeable by an external power source. The control apparatus includes a fuel deterioration determiner and a regeneration amount limiter. The fuel deterioration determiner determines whether a fuel stored in the fuel tank is deteriorated. The regeneration amount limiter reduces, when the fuel is determined by the fuel deterioration determiner as being deteriorated, a regeneration amount to be less than the regeneration amount of a case where the fuel is determined by the fuel deterioration determiner as not being deteriorated. The regeneration amount is an amount of regeneration of electric power generated by the electric motor upon deceleration of the plug-in hybrid electric vehicle.