In a pre-processing system, a state in which a sample dispensing probe 20a and a syringe pump 81 communicate with each other through a channel 91 and a state in which the sample dispensing probe 20a and a culture tank 301 communicate with each other through the channels 91, 93, and 94 can be switched by operation of the three-way valves 82 and 83. For this reason, the liquid sample in the culture tank 301 can be automatically discharged from the sample dispensing probe 20a without requiring the user to directly sample the liquid sample. As a result, in the pre-processing system, the user's manual sampling work can be omitted, and the user's work can be simplified.