There is provided an inspection method of an oxygen sensor, which includes a sensing portion having a reference electrode, a sensing electrode and an oxygen ion conducting solid electrolyte layer arranged between the reference electrode and the sensing electrode. The inspection method contains the steps of reading a first output value of the oxygen sensor under a condition that the sensing portion of the oxygen sensor is subjected to a first inspection gas and then a second output value of the oxygen sensor under a condition that the sensing portion of the oxygen sensor is subjected to a second inspection gas different in oxygen concentration from the first inspection gas and judging the oxygen sensor to be defective or nondefective based on the first and second output values.