A control apparatus which controls operation of an internal combustion engine including plural cylinders, characterized by comprising: a variable valve system in which the valve opening characteristic is varied an obtaining portion that determines a parameter concerning a valve opening characteristic of an intake valve of each of the plural cylinders; a combustion condition deciding portion that sets a combustion condition for each of the plural cylinders which combustion condition is determined by at least one of a fuel injection amount and ignition timing, according to the parameter; and a control portion that controls operation of each of the plural cylinders under the set combustion condition, wherein torque generated in each of the plural cylinders is determined according to the parameter and the combustion condition, and the combustion condition deciding portion sets the combustion condition such that a difference between the torque generated in each of the plural cylinders and reference torque is in a predetermined permissible range, wherein the control apparatus includes an operating state obtaining portion that obtains predetermined information concerning an operating state of the internal combustion engine, and the combustion condition deciding portion switches among plural modes of deciding the combustion condition that are prepared in advance, according to the obtained predetermined information; and wherein the internal combustion engine includes a catalyst that purifies exhaust gas; the operating state obtaining portion obtains, as the predetermined information, information on whether the catalyst has deteriorated in the form of a time-dependent decrease in the performance of said catalyst; and the combustion condition deciding portion adjusts both of the fuel injection amount and the ignition timing when the operating state obtaining portion obtains information that the catalyst has deteriorated in the form of a time-dependent decrease in the performance of said catalyst, and the combustion condition deciding portion adjusts only the fuel injection amount among the fuel injection amount and the ignition timing when the operating state obtaining portion obtains information that the catalyst has not deteriorated in the form of a time-dependent decrease in the performance of said catalyst. a variable valve system in which the valve opening characteristic is varied an obtaining portion that determines a parameter concerning a valve opening characteristic of an intake valve of each of the plural cylinders; a combustion condition deciding portion that sets a combustion condition for each of the plural cylinders which combustion condition is determined by at least one of a fuel injection amount and ignition timing, according to the parameter; and a control portion that controls operation of each of the plural cylinders under the set combustion condition, wherein torque generated in each of the plural cylinders is determined according to the parameter and the combustion condition, and the combustion condition deciding portion sets the combustion condition such that a difference between the torque generated in each of the plural cylinders and reference torque is in a predetermined permissible range, wherein the control apparatus includes an operating state obtaining portion that obtains predetermined information concerning an operating state of the internal combustion engine, and the combustion condition deciding portion switches among plural modes of deciding the combustion condition that are prepared in advance, according to the obtained predetermined information; and wherein the internal combustion engine includes a catalyst that purifies exhaust gas; the operating state obtaining portion obtains, as the predetermined information, information on whether the catalyst has deteriorated in the form of a time-dependent decrease in the performance of said catalyst; and the combustion condition deciding portion adjusts both of the fuel injection amount and the ignition timing when the operating state obtaining portion obtains information that the catalyst has deteriorated in the form of a time-dependent decrease in the performance of said catalyst, and the combustion condition deciding portion adjusts only the fuel injection amount among the fuel injection amount and the ignition timing when the operating state obtaining portion obtains information that the catalyst has not deteriorated in the form of a time-dependent decrease in the performance of said catalyst.