An apparatus for analyzing air/fuel ratio sensor characteristics makes it possible to perform highly accurate analysis of the characteristics of an air/fuel ratio sensor to be measured. The apparatus comprises a sensor attachment means in which is mounted an air/fuel ratio sensor to be measured; a gas regulation means for supplying to the sensor attachment means a gas that is substantially equivalent to components of exhaust gases from an engine, or some components thereof; a control means for comparing an output from the air/fuel ratio sensor to be measured mounted in the sensor attachment means and an output from a reference stoichiometric air/fuel ratio sensor at the stoichiometric air/fuel ratio of the engine, to obtain a deviation therebetween and to obtain from a history of this deviation over time the composition and flow rate of gases to be controlled to compensate for this deviation, and issuing appropriate instructions to the gas regulation means; and an air/ratio measurement means for measuring a time average of the thus controlled air/fuel ratio.