Being finishing method of the fluid dosage device, among the aforementioned fluid dosage devices, the processing object surface of 1 or more of the part which at least contacts with the fluid, the processing which it changes with the ion implantation which uses the multiplex energy ion beam of multiplex electric charge is included, the aforementioned sort as for the processing object surface which it can change, by the fact that formation of the living thing membrane is controlled, one side of appearance and multiplication of the bacterium in the processing object surface which it can change particularly or the quality which controls both possesses, aforementioned multiplex electric charge ion, is selected from helium, boron, carbon, nitrogen, oxygen, neon, argon, krypton and xenon,The finishing method, ion implantation being executed from 0 millimicrons to depth of 3 millimicrons.< Selective figure > Figure 1流体投与装置の表面処理方法であって、前記流体投与装置のうち、少なくとも流体と接触する部分の1以上の処理対象表面を、多重荷電の多重エネルギイオンビームを用いたイオン注入によって変化させる処理を含み、前記の通り変化させられた処理対象表面は、生物膜の形成を抑制することで、当該変化させられた処理対象表面における細菌の出現及び増殖の一方又は両方を抑制する特性を有し、前記多重荷電イオンは、ヘリウム、ホウ素、炭素、窒素、酸素、ネオン、アルゴン、クリプトン、キセノンから選択され、イオン注入は0μmから3μmの深さまで実施される、という表面処理方法。【選択図】 図1
