1. A response sensing device for an exhaust gas component concentration sensor, the response sensing device comprising: an intake air quantity measuring means provided to an intake pipe of a diesel engine for measuring an intake air quantity introduced into the diesel engine; an intake air quantity changing means for changing the intake air quantity of the diesel engine; an exhaust gas component concentration estimating means for estimating a component concentration of exhaust gas after combustion in the diesel engine at least based on the measured intake air quantity and a fuel injection quantity injected and supplied to the diesel engine; an exhaust gas component concentration sensor provided to an exhaust pipe of the diesel engine for sensing an actual component concentration of the exhaust gas of the diesel engine; and a response sensing means for sensing response of the exhaust gas component concentration sensor by comparing the exhaust gas component concentration estimated by the exhaust gas component concentration estimating means and the actual exhaust gas component concentration sensed by the exhaust gas component concentration sensor when compulsorily changing the intake air quantity with the intake air quantity changing means.