A control apparatus and method for a variable valve mechanism operated by an oil pressure by a variable displacement pump that is capable of varying its capacity. A control apparatus and a control method for a variable valve mechanism, by which deterioration of fuel efficiency and deterioration of operability can be suppressed, is provided. When controlling the variable valve mechanism that is operated by the oil pressure by a variable displacement pump, the control gain of the variable valve mechanism is changed, according to the capacity switching condition or the capacity switching operation of the variable valve mechanism. Driving the variable valve mechanism dependent on an actual hydraulic pressure state is enabled by changing the control gain of the variable valve mechanism in response to switching of the variable displacement pump, so that deterioration of fuel efficiency and operability can be inhibited while suppressing overshoot and response lag.