Oxygen sensor control apparatus for sensor calibration

In an oxygen sensor control apparatus, after start of fuel cut, the weighted average Ipd of corrected values obtained by multiplying the output value of a mounted oxygen sensor by a correction coefficient Kp is obtained as a representative value Ipe, representing the corrected values in the fuel cut period (S19). In the case where the number of times the representative value Ipe is continuously judged not to fall outside a second range (S21: NO) and to fall outside a first range (S23: YES) reaches 10 (a first number of times) (S26: YES), a new correction coefficient Kp is computed (S27). In the case where the number of times the representative value Ipe is continuously judged to fall outside the second range (S21: YES) reaches 4 (a second number of times) (S29: YES), a new correction coefficient Kp is computed (S30). Since the second number of times is smaller than the first number of times, when the representative value falls outside the second range, the correction coefficient can be computed at an earlier timing.