An apparatus for controlling an internal-combustion engine, the apparatus comprising: control means for adjusting at least one of a degree of opening of a throttle valve, a fuel injection of a fuel-injection valve and an ignition timing of an ignition plug, so as to control combustion of the internal-combustion engine; first idle speed control means for allowing the degree of opening of the throttle valve and the ignition timing to be adjusted and providing feedback control such that an engine speed generally corresponds to a target speed; and catalyst warm-up means for setting the fuel injection and the ignition timing to be at or after a compression top dead center so as to increase an exhaust temperature in a warm-up operation mode; the apparatus being characterized by comprising: second idle speed control means for inhibiting adjustment of the degree of opening of the throttle valve to the open side, advancing the ignition timing and providing feedback control such that the engine speed (rNe) generally corresponds to a target speed (tINe) when the catalyst warm-up means sets the fuel-injection and the ignition timing to be at or after the compression top dead center, wherein the degree of opening of the throttle valve is set, when the warming-up of the catalyst is requested, to be relatively large as compared with a case where the degree of opening of the throttle valve and the ignition timing are adjusted and the engine speed at least generally corresponds to the target speed, wherein the second idle speed control means decrease the engine speed (rNe) to the target speed (tINe) by decreasing the amount of intake air in accordance with the degree of opening of the throttle valve, and wherein the second idle speed control means increase the engine speed (rNe) to the target speed (tINe) by advancing the ignition timing without increasing the amount of intake air, the degree of opening of the throttle valve being inhibited from being adjusted to the open side. control means for adjusting at least one of a degree of opening of a throttle valve, a fuel injection of a fuel-injection valve and an ignition timing of an ignition plug, so as to control combustion of the internal-combustion engine; first idle speed control means for allowing the degree of opening of the throttle valve and the ignition timing to be adjusted and providing feedback control such that an engine speed generally corresponds to a target speed; and catalyst warm-up means for setting the fuel injection and the ignition timing to be at or after a compression top dead center so as to increase an exhaust temperature in a warm-up operation mode; the apparatus being characterized by comprising: second idle speed control means for inhibiting adjustment of the degree of opening of the throttle valve to the open side, advancing the ignition timing and providing feedback control such that the engine speed (rNe) generally corresponds to a target speed (tINe) when the catalyst warm-up means sets the fuel-injection and the ignition timing to be at or after the compression top dead center, wherein the degree of opening of the throttle valve is set, when the warming-up of the catalyst is requested, to be relatively large as compared with a case where the degree of opening of the throttle valve and the ignition timing are adjusted and the engine speed at least generally corresponds to the target speed, wherein the second idle speed control means decrease the engine speed (rNe) to the target speed (tINe) by decreasing the amount of intake air in accordance with the degree of opening of the throttle valve, and wherein the second idle speed control means increase the engine speed (rNe) to the target speed (tINe) by advancing the ignition timing without increasing the amount of intake air, the degree of opening of the throttle valve being inhibited from being adjusted to the open side. second idle speed control means for inhibiting adjustment of the degree of opening of the throttle valve to the open side, advancing the ignition timing and providing feedback control such that the engine speed (rNe) generally corresponds to a target speed (tINe) when the catalyst warm-up means sets the fuel-injection and the ignition timing to be at or after the compression top dead center, wherein the degree of opening of the throttle valve is set, when the warming-up of the catalyst is requested, to be relatively large as compared with a case where the degree of opening of the throttle valve and the ignition timing are adjusted and the engine speed at least generally corresponds to the target speed, wherein the second idle speed control means decrease the engine speed (rNe) to the target speed (tINe) by decreasing the amount of intake air in accordance with the degree of opening of the throttle valve, and wherein the second idle speed control means increase the engine speed (rNe) to the target speed (tINe) by advancing the ignition timing without increasing the amount of intake air, the degree of opening of the throttle valve being inhibited from being adjusted to the open side.