A knock control device of an internal combustion engine incorporated with a device for controlling the spark timing and the fuel injection.The device for controlling the spark timing and the fuel injection comprises an electronic control unit. A knock sensor is mounted on the cylinder block for sensing knocking. When the output of the knock sensor is above a first predetermined level, retardation of spark timing is caused. When the output of the knock sensor is above a second level above the first level, retardation of spark timing is caused and the amount of fuel to be injected is increased.