An engine system includes an engine and an engine control unit. The engine includes an intake valve that opens and closes the opening of a cylinder, a valve actuator that drives the intake valve and can arbitrarily control the lift amount of the intake valve, an intake passage that introduces air and fuel into the cylinder through the opening of the cylinder, and a throttle valve provided to open and close the opening of the intake passage and control the quantity of air to be introduced into the cylinder in response to a load required by a driver. During intake operation in substantially all the load states of the engine, the valve actuator is controlled so that the opening area of the opening determined by the lift amount of the intake valve is not less than the opening area of the opening determined by the opening degree of the throttle valve.