Abstract: A knock control apparatus for an internal combustion engine which prevents variation of a control knock sound even if an output of a knock sensor is varied due to the variations in performance among different engines or knock sensors, aging of the engine or knock sensor or the like. A given correction quantity is added to an average value of an output signal of the knock sensor, and the sum is increased K times by a K-value varying with the operating conditions of the engine, thereby generating a knock discrimination level. In accordance with the presence or absence of knocking determined by comparing the knock discrimination level and an output signal of the knock sensor, a knock control factor, e.g., ignition timing, supercharge pressure or the like of the engine is controlled.