PURPOSE: To easily mount and demount an elastic tube free from damage between a tube guide surface and a tube pressing member by selectively installing the tube pressing member between a normal position for fluid transfer and a retreat position from the pressing member for mounting and demounting the elastic tube.

CONSTITUTION: An elastic tube 6 is installed between a pressing roller 3 on a rotor member 2 and the tube guide 40 of a tube pressing member 4 which is set close to the circular motion orbit of the pressing roller 3 which is accompained with the revolution of the rotor member 2, and fluid transfer is carried out by squeezing the tube 6 by circular motion of the pressing roller 3. In this case, the tube pressing member 4 is selectively installed so as to be positioned at the normal position P1 for carrying out fluid transfer and the retreat position P2 for mounting and demounting the tube 6. Accordingly, the tube 6 can be easily mounted and demounted free from breakage between the tube guide surface 40 and the tube pressing roller 3.