PROBLEM TO BE SOLVED: To provide an endoscope washing and disinfecting apparatus capable of surely preventing an error that two endoscopes are inadvertently placed in a washing bath and washed and disinfected with an adapter attached to the washing bath.SOLUTION: A washing bath 21 comprises: airtight testing connectors 80 for supplying compressed air into the inside of an endoscope 10 and main-channel and sub-channel washing connectors 81, 82 for supplying a fluid to various channels of the endoscope 10. Two each of these components are provided for two endoscopes. An adapter 100 is attached to a washing bath 21 when one endoscope 10 is washed and disinfected. The adapter 100 comprises first and second cover parts 103, 104. A first cover part 103 covers and hides, from above, one airtight testing connector 80 and one main-channel washing connector 81 which are adjacent to each other. A second cover part 104 covers and hides, from above, one sub-channel washing connector 82.
