In an idling speed control method for adjusting the amount of intake air supplied to an internal combustion engine so that the engine speed matches a target speed when the engine is idling, a value of a stroke period or speed of the engine is detected. Further, a target torque improvement rate Mi, indicative of excess or deficiency of an engine output torque caused by a response delay in an intake system of the engine, is predicted in accordance with the detected value of the stroke period. Also, in accordance with the predicted torque improvement rate Mi, an ignition timing is delayed or advanced and the fuel supply quantity is increased or decreased to make an air-fuel ratio rich or lean. This eliminates the excess or deficiency of the intake air supply due to the response delay in the intake system relative to fluctuations in idling speed, thereby permitting stable idling even at low speed.