Abstract: An automatic focussing adjusting device which controls properly an integration time necessary to integrate the amount of light received by a CCD line sensor for measuring the light of an object to detect a focal position. In the automatic focussing adjusting device, when the average value of the output data of the CCD line sensor is a value existing out of the stable operation region of the CCD line sensor, the integration in time for the amount of the light received from the object by the CCD line sensor is controlled so that the average value of the next output data of the CCD line sensor converges rapidly to the reference value of the output data to be selected in the CCD line sensor stable operation region. For the average value existing in the stable operation region, the integration time is controlled so that the average value of the next output data converges slowly to the reference value.