GAS SENSOR

A gas sensor includes: an element body which is internally provided with a measurement-object gas flow portion; a first pump cell including a first inner electrode disposed in the measurement-object gas flow portion; a second pump cell including a second inner electrode disposed in the measurement-object gas flow portion; a heater; a first impedance measurer configured to measure a first impedance by applying a voltage to the first inner electrode; a second impedance measurer configured to measure a second impedance by applying a voltage to the second inner electrode; and a control apparatus configured to perform a heater control process of controlling the heater so that the first impedance reaches a target value, and a correction process of correcting, based on the second impedance, a second pump current which flows through the second pump cell or a value derived based on the second pump current.