To surely prevent disinfectant solution from being diluted by residual water.

The CPU 60 of the washing and disinfecting apparatus for an endoscope operates a first pump 45 to supply alcohol inside an alcohol tank 42 through an alcohol supply path 44 to a nozzle 20 and a coupler 32 immediately before a disinfection process, operates a jetting device 15 to jet the alcohol from the nozzle 20 and performs a replacement process of replacing water remaining in the inner pipeline of the endoscope 30, on an outer surface and on the surface of a washing tub 12 with the alcohol. Since the disinfectant solution is not diluted by the residual water, the number of times of recycling the disinfectant solution increases and a running cost is reduced.