The driving unit 40 moves the upstream side closing member 31 and the downstream side closing member 35 in the pressing direction to close the liquid receiving tube 102 and then moves the pressing force holding member 32 in the pressing direction, Thereby increasing the internal pressure of the tube 102. Thereafter, the specified amount of pressure member 34 is moved in the pushing direction, and the downstream side closing member 35 is moved in the opposite direction of pressing to open the downstream side of the liquid-receiving tube 102.구동부(40)는, 상류측 폐색부재(31) 및 하류측 폐색부재(35)를 누름방향으로 이동시켜 수액튜브(102)를 폐색한 후, 규정력 누름부재(32)를 누름방향으로 이동시켜 수액튜브(102)의 내압을 높인다. 그 후, 규정량 누름부재(34)를 누름방향으로 이동시킴과 더불어, 하류측 폐색부재(35)를 누름 반대방향으로 이동시켜 수액튜브(102)의 하류측을 개방한다.
