To reduce an insufficient torque caused by the sudden acceleration of a vehicle, in an exhaust emission control device for an internal combustion engine performing rich combustion in order to reduce NOx occluded in a NOx catalyst.

An acceleration rate a of the vehicle is obtained (S21). Whether or not a sudden acceleration of the vehicle should be performed is determined (S22) by determining whether or not the acceleration rate a is higher than a predetermined threshold acceleration rate b. When it is determined that the sudden acceleration of the vehicle should be performed (S22:YES), a permission determination flag F for permitting the performance of the rich combustion is set to OFF (F=0) (S23), and normal combustion is performed instead of performing the rich combustion. Since torque is controlled by controlling the amount of fuel injected with respect to fresh air volume in the normal combustion, the torque can be controlled to target torque by adjusting the amount of fuel injected even if the fresh air volume can not follow target air volume in some degree. Therefore, cases of insufficient torque can be reduced.

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