A vehicle comprising: an internal combustion engine having a plurality of cylinders; an exhaust gas purification catalyst which is arranged in an exhaust passage of the internal combustion engine and purifies exhaust gas; first air-fuel ratio detecting means arranged upstream of the exhaust gas purification catalyst; second air-fuel ratio detecting means arranged downstream of the exhaust gas purification catalyst; and a control apparatus of the internal combustion engine, wherein the control apparatus executes main feedback control that controls an air-fuel ratio of the internal combustion engine based on a detection value of the first air-fuel ratio detecting means, and sub-feedback control that calculates a learning value for correcting the main feedback control based on a detection value of the second air-fuel ratio detecting means; and wherein the controlling apparatus includes rotational variation calculating means for calculating a rotational variation of an output shaft of the internal combustion engine based on combustion of each of the cylinders; variation integrating means for calculating a cumulative value of the rotational variation by adding the rotational variation calculated by the rotational variation calculating means to the rotational variation integrated thus far; integration counting means for counting the number of times the rotational variation has been integrated by the variation integrating means; combustion state estimating means for estimating a combustion state of the internal combustion engine according to the cumulative value of the rotational variation integrated by the variation integrating means, on the condition that the number of integrations counted by the integration counting means has reached a predetermined value; and learning value correcting means for correcting the learning value of the sub-feedback control according to the combustion state estimated by the combustion state estimating means. an internal combustion engine having a plurality of cylinders; an exhaust gas purification catalyst which is arranged in an exhaust passage of the internal combustion engine and purifies exhaust gas; first air-fuel ratio detecting means arranged upstream of the exhaust gas purification catalyst; second air-fuel ratio detecting means arranged downstream of the exhaust gas purification catalyst; and a control apparatus of the internal combustion engine, wherein the control apparatus executes main feedback control that controls an air-fuel ratio of the internal combustion engine based on a detection value of the first air-fuel ratio detecting means, and sub-feedback control that calculates a learning value for correcting the main feedback control based on a detection value of the second air-fuel ratio detecting means; and wherein the controlling apparatus includes rotational variation calculating means for calculating a rotational variation of an output shaft of the internal combustion engine based on combustion of each of the cylinders; variation integrating means for calculating a cumulative value of the rotational variation by adding the rotational variation calculated by the rotational variation calculating means to the rotational variation integrated thus far; integration counting means for counting the number of times the rotational variation has been integrated by the variation integrating means; combustion state estimating means for estimating a combustion state of the internal combustion engine according to the cumulative value of the rotational variation integrated by the variation integrating means, on the condition that the number of integrations counted by the integration counting means has reached a predetermined value; and learning value correcting means for correcting the learning value of the sub-feedback control according to the combustion state estimated by the combustion state estimating means.