A chemical liquid supplying apparatus, which can discharge chemical liquid with high precision, is provided. A pump assembly is detachably mounted in a pump case in which liquid inflow and discharge ports are formed. The pump assembly includes: a cylindrical body in which a piston is slidably incorporated axially; an elastically deformable bellows forming a pump chamber in the pump case and forming a drive chamber in which an indirect medium is enclosed; and an axially elastically-deformable bellows cover continuing with a sliding surface of the piston and forming a seal chamber in which the indirect medium is enclosed, and the pump assembly is unitized. The pump assembly is coupled to a drive shaft via a connecting member, and by axial-directional reciprocating movement of this drive shaft, the piston causes the bellows to perform a pump operation, whereby the chemical liquid is discharged from a liquid discharge portion.