A sample preprocessing system is capable of reducing centrifuging time, which accounts for the majority of time required for a preprocessing step, and at the same time, performing centrifuging under various conditions. A system management unit ascertains the states of a plurality of centrifuge devices, particularly comparing centrifuging start times and centrifuging termination times for the respective centrifuge devices, and selects the centrifuge device for which the processing time is shortest. Specifically, the system includes an adapter that forms a plurality of batches, a gripper to transfer a sample to the adapter, a plurality of centrifuge rotors that centrifuge the adapter in batch units, and a computer programmed to calculate, in advance, a start timing and a termination timing of the centrifuging in batch units, and the batch, into which samples are transferred, is controlled on the basis of at least one of the calculated start timing and termination timing.