PROBLEM TO BE SOLVED: To provide a liquid extraction device body capable of performing sterilization treatment.SOLUTION: A liquid extraction device body 10 forward/backward moves a piston 33 inside a cylindrical body 20 along the axial direction of the piston 33 by drive of a rotation actuator 31, and sucks and extracts liquid via a syringe cartridge 100 fitted to a tip end side. The piston 33 includes a seal part 60 that fills a gap between an outer peripheral surface of the piston 33 and an inner peripheral surface of the cylindrical body 20 in a retractable manner and prevents gas from flowing from the outside into the rotation actuator 31 side through the gap.SELECTED DRAWING: Figure 2