A fluid feeder (1, 31) which feeds a fluid into a balloon (4) made of an elastic material so as to inflate, the fluid feeder provided with: a cylinder (12) that is formed in a cylindrical shape provided with a first end (12A) and a second port (12B) on each end thereof and contains the fluid； a plunger (13) that is inserted into the cylinder via the second end in a freely advancing and retracting manner in an axial direction, in order to push out the fluid contained in the cylinder from the first end to the outside of the cylinder； an adjustor (14, 32) that is attached to the plunger and regulates a moving distance of the plunger so as to inflate the balloon to a predetermined diameter； and a fixing portion (15) that is provided on the cylinder and fixes the plunger onto the cylinder to a position which corresponds to the moving distance regulated by the adjustor, wherein:the adjustor has a plurality of engaging projections (18, 33) which regulates the moving distance corresponding to a plurality of the different inflated diameters, and the fixing portion has an engaged portion (19) which engages with the engaging projections to fix the plunger.
