PURPOSE: To prevent worsening of operation performance when an ignition timing is delayed for early activation of a catalyst.

CONSTITUTION: An air amount control device for an internal combustion engine comprises a means 2 to calculate an amount of a an angle of delay of an ignition timing, required for activation of a catalyst, from an operation condition, a means 3 to output an ignition signal by means of which a fundamental ignition timing is corrected according to the amount of an angle of delay, a means 4 to compute a correction amount of the increase of intake air according to the quantity of an angel of delay of the ignition timing and an amount of intake air or a throttle valve opening signal, and an air amount control means 5 to increase an amount of intake air according to the correction amount of an increase. The control device is further provided with a delay compensating means 6 to correct a correction amount of an increase according to an intake air manifold volume and an engine load and an air amount control means 5 to increase an intake air amount according to the correction amount.