PURPOSE: To enable the control of the storage time of a storage type image sensor CCD at a high respone without hunting by correcting adequately the image signal from the CCD accoding to the size of the integration level thereof.

CONSTITUTION: The time serial image signal from a storage type image sensor CCD 7 is converted to electric current by a voltage-current conversion circuit 81, whereafter the current is integrated in an integration circuit 82. The integrated output voltage is compared with a reference voltage value 83 indicating the level of the correct quantity of light. The rate of correction corresponding to the difference thereof is inputted to a circuit 85 for varying storage time. The circuit 85 generates the shift pulse corresponding to the rate of correction inputted thereto and controls the period of the shift pulses of the CCD 7, that is, the storage time of the CCD 7. Then, if the integration level from the image signal is deviated large from the level of the correct quantity of light, the correction is thoroughly accomplished and if the difference is small, the rate of correction is decreased; therefore, the storage time of the CCD is controlled at a fast response without hunting.