A gasoline engine includes an electric heater, which is embedded in a port-type fuel injection valve and heats the fuel in the fuel injection valve. An electronic control device heats the fuel by means of the electric heater when the engine is cold. When the fuel is not heated by the electric heater, the electronic control device controls the fuel injection valve such that the engine rotational speed NE is a second prescribed value N2 which is higher than the idle rotational speed when the engine is warm. When idle running is performed when the engine is cold and the fuel injected from the fuel injection valve is heated by the electric heater, the amount Q of fuel injected by the fuel injection valve is controlled such that the engine rotational speed NE is less than the second prescribed value N2.