When it is detected that any one of a plurality of variable valve characteristic mechanisms disposed for every cylinder groups is failed, an effective opening degree (valve lift amount, valve operating angle or the like) in a valve characteristic in the failed state, is obtained. When the effective opening degree is judged to be a predetermined value or above, the valve characteristic of the normal variable valve characteristic mechanism is controlled to be coincident with the valve characteristic in the failed state. When the effective opening degree is judged to be less than the predetermined value, there is performed a control for limiting the control to coincide the valve characteristic of the normal variable valve characteristic mechanism with the valve characteristic in the failed state.