AIR-FUEL RATIO DETECTION DEVICE AND AIR-FUEL RATIO DETECTION METHOD

An air-fuel ratio detection device ′ comprises: a sensor element ′ including a sensor cell ; a voltage application circuit ′ applying voltage to the sensor cell; a current detector ′ detecting an output current of the sensor cell; an air-fuel ratio calculating part configured to calculate an air-fuel ratio of an exhaust gas; and a parameter detecting part configured to detect or calculate a temperature correlation parameter correlated with a temperature of the sensor element. The air-fuel ratio calculating part is configured to calculate the air-fuel ratio of the exhaust gas based on the temperature correlation parameter and the output current detected when a predetermined voltage is applied to the sensor cell.