PURPOSE: To automatically and easily carry out priming work by constituting the title device so as to connect an incoming channel to an outgoing channel with the thrust-pressure of an elastic body when the pressure of fluid becomes the same as the prescribed pressure.

CONSTITUTION: A flow control device 14 is approximately T-shaped to a first tube member 30 connected to a tube 13, and consists of a second tube member 32 connected to the first tube member 30 and an elastic body 34 installed on the edge part of the first tube member 30. When the pressure of a liquid transporting agent supplied into the incoming channel 42 and a throughout channel 44 is increased by driving a syringe pump, the liquid transporting agent in the throughout channel 44 passes through the gap between the elastic body 34 and a rod part 40, and flows from the boundary part between a rod part 38 of the first tube member 30 and the rod part 40 to the side of an outgoing channel 52.