An endoscope cleaning/disinfecting apparatus of the invention includes: a processing tank including an opening portion; an apparatus main body which performs processing on an endoscope arranged in the processing tank; a lid member which opens and closes the opening portion; an electric actuator which is connected to the lid member and which generates a pressing force for pressing the lid member toward the opening portion; and a control section connected to the apparatus main body and the electric actuator, the control section causing the electric actuator to continue to generate the pressing force for pressing the lid member toward the opening portion in a predetermined period during execution of the processing, and causing the electric actuator to stop generating the pressing force in a period other than the predetermined period.