Gas sensor control apparatus and gas sensor control method

A catalytic conversion characteristic of a catalyst, which indicates a relationship between an air-to-fuel ratio and a catalytic conversion efficiency of the catalyst, includes a second air-to-fuel ratio point, which is a point of starting an outflow of NOx from the catalyst and is located on a rich side of a first air-to-fuel ratio point that forms an equilibrium point for a rich component and oxygen. A constant current circuit (43), which induces a flow of an electric current from an exhaust side electrode (33) to an atmosphere side electrode (34) through a solid electrolyte layer (32) in a sensor element (31), is connected to the sensor element (31). A microcomputer (41) controls a current value of the electric current, which is induced by the constant current circuit (43), based on a difference between the first air-to-fuel ratio point and the second air-to-fuel ratio point at the catalyst.