Abnormality detection device for exhaust gas sensor

An abnormality detection device configured to determine abnormality in an exhaust gas sensor configured to be disposed in an exhaust passage of an internal combustion engine and to detect a component in exhaust gas, the abnormality detection device comprising:

• a responsiveness determination unit configured to calculate responsiveness of the exhaust gas sensor on the basis of a timewise change of output values of the exhaust gas sensor;
• and
• an abnormality determination unit configured to determine that the exhaust gas sensor has abnormality when the responsiveness calculated by the responsiveness determination unit is lower than a predetermined responsiveness threshold,
• wherein the abnormality determination unit is configured to determine if the exhaust gas sensor has abnormality, excluding an excluded period during which a slope of the output values becomes zero or is inversed with respect to a preceding trend of the timewise change while the output values of the exhaust gas sensor timewisely change between a predetermined first determination value and a second determination value.