A spark timing control apparatus controls the spark timing to retard or advance in accordance with the output signal from a knock sensor. An accelerating condition of the engine is determined depending on a particular knock occurence patterns including; whether the interval of knock occurences is larger or small, the total amount of retard angles is larger or small, or the frequency of knock occurences. When the accelerating condition is determined, the advancing rate of the spark timing is increased until a steady state of the engine operation is determined based on the output signal of the knock sensor.