Preprocessing method and preprocessing apparatus

A preprocessing apparatus, comprising:

• a container holding unit that holds a sample container;
• a suction tube mounting unit to which a suction tube is detachably mounted;
• a suction and discharge unit that suctions and discharges a liquid with respect to the sample container held by the container holding unit through the suction tube mounted to the suction tube mounting unit;
• a centrifugation unit;
• a container moving unit that grips the sample container and moves the sample container between the container holding unit and the centrifugation unit;
• and a control unit that controls the suction and discharge unit and the container moving unit, wherein the control unit is configured to sequentially perform, on the same sample, a first unit preprocessing and a second unit preprocessing, which are unit preprocessing for sequentially performing:
• a solvent addition step of adding a solvent to the sample container held by the container holding unit to prepare a mixture of a sample and the solvent;
• a first moving step of moving the sample container from the container holding unit to the centrifugation unit;
• a second moving step of moving the sample container, after the mixture has been centrifuged in the centrifugation unit, to the container holding unit;
• and a suction step of inserting the suction tube into the sample container held by the container holding unit such that a height of a tip thereof from a bottom of the sample container becomes a predetermined height, and suctioning a supernatant of the mixture with the suction tube, wherein the first unit preprocessing sets the predetermined height in the suction step to a first height, and the second unit preprocessing sets the predetermined height in the suction step to a second height that is higher than the first height.