A cleaning and sterilizing apparatus which provides alkaline-water-cleaning removing organic matter adhered to the surface of an endoscopic camera instrument, and effectively exhibiting bacteria-killing and virus-killing effects of acidic water, is provided.The apparatus uses as cleaning bath an alkaline-water-producing bath 2 of an electrolysis bath 1 partitioned by a separating membrane 6 and having electrodes 7 and 8 on both sides, and the apparatus is configured to conduct preliminary cleaning of an endoscopic camera instrument 4 inserted in the cleaning bath by ultrasonic cleaning with city water, subsequently provides saline solution to the electrolysis bath to conduct electrolysis, conduct ultrasonic cleaning with alkaline water obtained by the electrolysis, introduce acidic water in the acidic water generation bath 3 and conduct sterilization-cleaning, and further, conduct ultrasonic cleaning with city water. Then, the apparatus dries the endoscopic camera instrument 4 with warm air as the case requires.