In a chemical liquid supplying apparatus, discharge accuracy of chemical liquid is enhanced, and durability of a flexible tube is enhanced. By the flexible tube incorporated into a pump housing, an interior of the pump housing is partitioned into a pump chamber, which communicates with a liquid inlet and a liquid outlet, and a drive chamber in which an incompressible, indirect medium is enclosed. Outer surfaces of end portions of the flexible tube are sealed by outer seal members, and their inner surfaces are sealed by inner seal members. Fastening cylindrical bodies disposed in the end portions of the flexible tube are radially expanded by wedge sleeves, whereby the outer and inner seal members are caused to closely contact with the flexible tube.