A control device for a compressed self-ignition type internal combustion engine, for use in an internal combustion engine having: - an injector for directly injecting fuel into a combustion chamber; and - an ignition device for igniting the fuel injected into the combustion chamber, the control device for a compressed self-ignition type internal combustion engine being configured such that: a spark-ignition type combustion mode in which fuel sprayed from the injector is ignited by the ignition device to burn the fuel to actuate the internal combustion engine, and a compressed self-ignition type combustion mode, in which the fuel injected from the injector is caused to burn by a pressure rise in association with upward movement of a piston making up the combustion chamber, are switched depending on whether or not the working state of the internal combustion engine is in a compressed self-ignition type combustion region in which the compressed self-ignition type combustion mode is stably performable, which is determined by a torque and an engine rotational speed, and that when an air-fuel ratio which is a mass ratio between an air quantity and a fuel quantity introduced into the combustion chamber while the compressed self-ignition type combustion mode is performed is richer than a predetermined value, an upper limit of torque of the compressed self-ignition type combustion region is changed toward a direction in which the upper limit decreases, whereby the air-fuel ratio is determined based on an output signal of a sensor for detecting air-fuel ratio, which is provided in the downstream of the exhaust valve. - an injector for directly injecting fuel into a combustion chamber; and - an ignition device for igniting the fuel injected into the combustion chamber, the control device for a compressed self-ignition type internal combustion engine being configured such that: a spark-ignition type combustion mode in which fuel sprayed from the injector is ignited by the ignition device to burn the fuel to actuate the internal combustion engine, and a compressed self-ignition type combustion mode, in which the fuel injected from the injector is caused to burn by a pressure rise in association with upward movement of a piston making up the combustion chamber, are switched depending on whether or not the working state of the internal combustion engine is in a compressed self-ignition type combustion region in which the compressed self-ignition type combustion mode is stably performable, which is determined by a torque and an engine rotational speed, and that when an air-fuel ratio which is a mass ratio between an air quantity and a fuel quantity introduced into the combustion chamber while the compressed self-ignition type combustion mode is performed is richer than a predetermined value, an upper limit of torque of the compressed self-ignition type combustion region is changed toward a direction in which the upper limit decreases, whereby the air-fuel ratio is determined based on an output signal of a sensor for detecting air-fuel ratio, which is provided in the downstream of the exhaust valve. a spark-ignition type combustion mode in which fuel sprayed from the injector is ignited by the ignition device to burn the fuel to actuate the internal combustion engine, and a compressed self-ignition type combustion mode, in which the fuel injected from the injector is caused to burn by a pressure rise in association with upward movement of a piston making up the combustion chamber, are switched depending on whether or not the working state of the internal combustion engine is in a compressed self-ignition type combustion region in which the compressed self-ignition type combustion mode is stably performable, which is determined by a torque and an engine rotational speed, and that when an air-fuel ratio which is a mass ratio between an air quantity and a fuel quantity introduced into the combustion chamber while the compressed self-ignition type combustion mode is performed is richer than a predetermined value, an upper limit of torque of the compressed self-ignition type combustion region is changed toward a direction in which the upper limit decreases, whereby the air-fuel ratio is determined based on an output signal of a sensor for detecting air-fuel ratio, which is provided in the downstream of the exhaust valve.