An exhaust emission control device which is capable of supplying a just enough amount of reducing agent to a NOx catalyst while causing the amount of reducing agent consumed in an upstream catalyst to be reflected thereon. A NOx catalyst for trapping NOx and reducing NOx to change the same into harmless ingredients in a reducing atmosphere is disposed downstream of a catalyst. Reducing agent is supplied upstream of the catalyst to cause the NOx catalyst to perform a NOx-reducing action. The amount of oxygen occluded in the catalyst is calculated. During reduction control, according to the oxygen occlusion amount, the amount of reducing agent oxidized and consumed in the catalyst is calculated. According to the reducing agent consumption amount, the amount of reducing agent supplied to the NOx catalyst is calculated. The reduction control is terminated based on the reducing agent supply amount.