A control apparatus for an internal combustion engine that includes a turbo-supercharger and an exhaust gas purifying catalyst disposed in an exhaust passage on a downstream side of a turbine of the turbo-supercharger, the control apparatus comprising: a throttle valve that adjusts an intake air amount that is drawn into the internal combustion engine; an ignition device for igniting an air-fuel mixture in a cylinder of the internal combustion engine; an exhaust bypass passage that branches from the exhaust passage on an upstream side of the turbine, and merges again with the exhaust passage at a location between the turbine and the exhaust gas purifying catalyst; a waste gate valve that is capable of opening and closing the exhaust bypass passage; catalyst warm-up execution means for executing catalyst warm-up control that opens the waste gate valve and retards an ignition timing at a time of a catalyst warm-up request to warm up the exhaust gas purifying catalyst; characterized by further comprising actuator change means for selecting in accordance with whether or not a pressure difference between an upstream pressure and a downstream pressure of the throttle valve during execution of the catalyst warm-up control is equal to or less than a predetermined value, an intake air amount control actuator (30 or 42) that is used to obtain a required intake air amount during execution of the catalyst warm-up control, wherein the actuator change means selects the throttle valve as the intake air amount control actuator (30 or 42) when the pressure difference is not equal to or not less than the predetermined value, while selecting the waste gate valve as the intake air amount control actuator (30 or 42) when the pressure difference is equal to or less than the predetermined value, ignition timing control means for increasing a retard amount of an ignition timing when a degree of opening of the waste gate valve is controlled toward a closed side in a case where the waste gate valve is being selected as the intake air amount control actuator (30 or 42). a throttle valve that adjusts an intake air amount that is drawn into the internal combustion engine; an ignition device for igniting an air-fuel mixture in a cylinder of the internal combustion engine; an exhaust bypass passage that branches from the exhaust passage on an upstream side of the turbine, and merges again with the exhaust passage at a location between the turbine and the exhaust gas purifying catalyst; a waste gate valve that is capable of opening and closing the exhaust bypass passage; catalyst warm-up execution means for executing catalyst warm-up control that opens the waste gate valve and retards an ignition timing at a time of a catalyst warm-up request to warm up the exhaust gas purifying catalyst; characterized by further comprising actuator change means for selecting in accordance with whether or not a pressure difference between an upstream pressure and a downstream pressure of the throttle valve during execution of the catalyst warm-up control is equal to or less than a predetermined value, an intake air amount control actuator (30 or 42) that is used to obtain a required intake air amount during execution of the catalyst warm-up control, wherein the actuator change means selects the throttle valve as the intake air amount control actuator (30 or 42) when the pressure difference is not equal to or not less than the predetermined value, while selecting the waste gate valve as the intake air amount control actuator (30 or 42) when the pressure difference is equal to or less than the predetermined value, ignition timing control means for increasing a retard amount of an ignition timing when a degree of opening of the waste gate valve is controlled toward a closed side in a case where the waste gate valve is being selected as the intake air amount control actuator (30 or 42).