The invention provides a disinfection device. The disinfection liquid is recovered from a cleaning slot to a disinfection tank after the completion of the cleaning disinfection processing of the endoscope in the cleaning slot. After the recovery of the disinfection liquid, a concentration measurement control portion (157) measures the concentration of the disinfection liquid at the concentration sensor (132). The concentration measured by the concentration sensor (132) is inputted into a determination portion (158), and it is determined whether it is suitable for performing disinfection for the endoscope within the range of the concentration value. An input control portion (161) outputs the cleaning information including the determination result to each output target. The cleaning controlportion (155) removes the locking mechanism (23) of the top cover of the cleaning slot when the determination result is appropriate. When the determination result is not appropriate, the locking stateof the locking mechanism is maintained before the further disinfection of the endoscope by the novel disinfection liquid. In another embodiment, when the determination result is not appropriate, rawliquid is supplied to the disinfection liquid into the disinfection liquid tank.
